diff --git a/Jenkinsfile b/Jenkinsfile
index 78c9e6be934..306cf6c76aa 100644
--- a/Jenkinsfile
+++ b/Jenkinsfile
@@ -7,9 +7,9 @@ def runTests(String testPath, boolean jumbo = false) {
         sh "cat make/local"
         sh "make print-compiler-flags"
         if (jumbo && !params.disableJumbo) {
-            sh "python3 runTests.py -j${env.PARALLEL} ${testPath} --jumbo --debug"
+            sh "python3 runTests.py -j${PARALLEL} ${testPath} --jumbo --debug"
         } else {
-            sh "python3 runTests.py -j${env.PARALLEL} ${testPath}"
+            sh "python3 runTests.py -j${PARALLEL} ${testPath}"
         }
     }
         finally { junit 'test/**/*.xml' }
@@ -61,7 +61,6 @@ pipeline {
         OPENCL_PLATFORM_ID = 1
         OPENCL_PLATFORM_ID_CPU = 0
         OPENCL_PLATFORM_ID_GPU = 0
-        PARALLEL = 4
         GIT_AUTHOR_NAME = 'Stan Jenkins'
         GIT_AUTHOR_EMAIL = 'mc.stanislaw@gmail.com'
         GIT_COMMITTER_NAME = 'Stan Jenkins'
@@ -173,305 +172,7 @@ pipeline {
             post { always { retry(3) { deleteDir() } } }
         }
 
-        stage('Quick tests') {
-            when {
-                expression {
-                    !skipRemainingStages
-                }
-            }
-            failFast true
-            parallel {
-                stage('Headers check') {
-                    when {
-                        expression {
-                            !skipRemainingStages
-                        }
-                    }
-                    agent {
-                        docker {
-                            image 'stanorg/ci:gpu-cpp17'
-                            label 'linux'
-                        }
-                    }
-
-                    steps {
-                        retry(1){
-                            unstash 'MathSetup'
-                            sh "echo CXX=${CLANG_CXX} -Werror > make/local"
-                            sh "make -j${PARALLEL} test-headers"
-                        }
-                    }
-                    post { always { deleteDir() } }
-                }
-                stage('Run changed unit tests') {
-                    agent {
-                        docker {
-                            image 'stanorg/ci:gpu-cpp17'
-                            label 'linux'
-                            args '--cap-add SYS_PTRACE'
-                        }
-                    }
-                    when {
-                        allOf {
-                            expression {
-                                env.BRANCH_NAME ==~ /PR-\d+/
-                            }
-                            expression {
-                                !skipRemainingStages
-                            }
-                        }
-                    }
-                    steps {
-                        retry(3) { checkout scm }
-
-                        sh "echo CXXFLAGS += -fsanitize=address >> make/local"
-                        sh "./runTests.py -j${PARALLEL} --changed --debug"
-
-                    }
-                    post { always { retry(3) { deleteDir() } } }
-                }
-            }
-        }
-
-        stage('Full Unit Tests') {
-            when {
-                expression {
-                    !skipRemainingStages
-                }
-            }
-            failFast true
-            parallel {
-                stage('Rev/Fwd Unit Tests') {
-                    agent {
-                        docker {
-                            image 'stanorg/ci:gpu-cpp17'
-                            label 'linux'
-                            args '--cap-add SYS_PTRACE'
-                        }
-                    }
-                    when {
-                        expression {
-                            !skipRemainingStages
-                        }
-                    }
-                    steps {
-                        unstash 'MathSetup'
-                        sh "echo CXXFLAGS += -fsanitize=address >> make/local"
-
-                        script {
-                            if (!(params.optimizeUnitTests || isBranch('develop') || isBranch('master'))) {
-                                sh "echo O=0 >> make/local"
-                            }
-
-                            runTests("test/unit/math/rev")
-                            runTests("test/unit/math/fwd")
-                        }
-                    }
-                    post { always { retry(3) { deleteDir() } } }
-                }
-                stage('Mix Unit Tests') {
-                    agent {
-                        docker {
-                            image 'stanorg/ci:gpu-cpp17'
-                            label 'linux'
-                            args '--cap-add SYS_PTRACE'
-                        }
-                    }
-                    when {
-                        expression {
-                            !skipRemainingStages
-                        }
-                    }
-                    steps {
-                        unstash 'MathSetup'
-                        sh "echo CXXFLAGS += -fsanitize=address >> make/local"
-                        script {
-                            if (!(params.optimizeUnitTests || isBranch('develop') || isBranch('master'))) {
-                                sh "echo O=1 >> make/local"
-                            }
-                            runTests("test/unit/math/mix", true)
-                        }
-                    }
-                    post { always { retry(3) { deleteDir() } } }
-                }
-                stage('Prim Unit Tests') {
-                    agent {
-                        docker {
-                            image 'stanorg/ci:gpu-cpp17'
-                            label 'linux'
-                            args '--cap-add SYS_PTRACE'
-                        }
-                    }
-                    when {
-                        expression {
-                            !skipRemainingStages
-                        }
-                    }
-                    steps {
-                        unstash 'MathSetup'
-                        sh "echo CXXFLAGS += -fsanitize=address >> make/local"
-                        script {
-                            if (!(params.optimizeUnitTests || isBranch('develop') || isBranch('master'))) {
-                                sh "echo O=0 >> make/local"
-                            }
-                            runTests("test/unit/*_test.cpp", false)
-                            runTests("test/unit/math/*_test.cpp", false)
-                            runTests("test/unit/math/prim", true)
-                            runTests("test/unit/math/memory", false)
-                        }
-                    }
-                    post { always { retry(3) { deleteDir() } } }
-                }
-                stage('Laplace Unit Tests') {
-                    agent {
-                        docker {
-                            image 'stanorg/ci:gpu-cpp17'
-                            label 'linux'
-                            args '--cap-add SYS_PTRACE'
-                        }
-                    }
-                    when {
-                        expression {
-                            !skipRemainingStages
-                        }
-                    }
-                    steps {
-                        unstash 'MathSetup'
-                        sh "echo CXXFLAGS += -march=native -mtune=native >> make/local"
-                        sh "echo O=3 >> make/local"
-                        script {
-                            if (params.optimizeUnitTests || isBranch('develop') || isBranch('master')) {
-                                sh "echo CXXFLAGS += -fsanitize=address >> make/local"
-                            }
-                            runTests("test/unit/math/laplace/*_test.cpp", false)
-                        }
-                    }
-                    post { always { retry(3) { deleteDir() } } }
-                }
-                stage('OpenCL GPU tests') {
-                    agent {
-                        docker {
-                            image 'stanorg/ci:gpu-cpp17'
-                            label 'v100'
-                            args '--gpus 1'
-                        }
-                    }
-                    steps {
-                        script {
-                            unstash 'MathSetup'
-                            sh """
-                                echo CXX=${CLANG_CXX} -Werror > make/local
-                                echo STAN_OPENCL=true >> make/local
-                                echo OPENCL_PLATFORM_ID=${OPENCL_PLATFORM_ID_GPU} >> make/local
-                                echo OPENCL_DEVICE_ID=${OPENCL_DEVICE_ID_GPU} >> make/local
-                            """
-                            if (!(params.optimizeUnitTests || isBranch('develop') || isBranch('master'))) {
-                                sh "echo O=1 >> make/local"
-                            }
-                            runTests("test/unit/math/opencl", false) // TODO(bward): try to enable
-                            runTests("test/unit/multiple_translation_units_test.cpp")
-                        }
-                    }
-                    post { always { retry(3) { deleteDir() } } }
-                }
-            }
-        }
-        stage('Always-run tests') {
-            when {
-                expression {
-                    !skipRemainingStages
-                }
-            }
-            failFast true
-            parallel {
-                stage('MPI tests') {
-                    agent {
-                        docker {
-                            image 'stanorg/ci:gpu-cpp17'
-                            label 'linux'
-                        }
-                    }
-                    steps {
-                        unstash 'MathSetup'
-                        sh """
-                            echo CXX=${MPICXX} > make/local
-                            echo CXX_TYPE=gcc >> make/local
-                            echo STAN_MPI=true >> make/local
-                        """
-                        runTests("test/unit/math/prim/functor")
-                        runTests("test/unit/math/rev/functor")
-                    }
-                    post { always { retry(3) { deleteDir() } } }
-                }
-                stage('Expressions test') {
-                    agent {
-                        docker {
-                            image 'stanorg/ci:gpu-cpp17'
-                            label 'linux'
-                        }
-                    }
-                    steps {
-                        unstash 'MathSetup'
-                        script {
-                            sh "echo O=0 > make/local"
-                            sh "echo CXX=${CLANG_CXX} -Werror >> make/local"
-                            sh "python ./test/code_generator_test.py"
-                            sh "python ./test/signature_parser_test.py"
-                            sh "python ./test/statement_types_test.py"
-                            sh "python ./test/varmat_compatibility_summary_test.py"
-                            sh "python ./test/varmat_compatibility_test.py"
-                            withEnv(['PATH+TBB=./lib/tbb']) {
-                                sh "python ./test/expressions/test_expression_testing_framework.py"
-                                sh "cat make/local"
-                                try { sh "./runTests.py -j${PARALLEL} test/expressions" }
-                                finally { junit 'test/**/*.xml' }
-                            }
-                            sh "make clean-all"
-                            sh "echo STAN_THREADS=true >> make/local"
-                            withEnv(['PATH+TBB=./lib/tbb']) {
-                                try {
-                                    sh "cat make/local"
-                                    sh "./runTests.py -j${PARALLEL} test/expressions --only-functions reduce_sum map_rect"
-				                }
-                                finally { junit 'test/**/*.xml' }
-                            }
-                        }
-                    }
-                    post { always { deleteDir() } }
-                }
-
-                stage('Threading tests') {
-                    agent {
-                        docker {
-                            image 'stanorg/ci:gpu-cpp17'
-                            label 'linux'
-                        }
-                    }
-                    steps {
-                        script {
-                            retry(1){
-                                unstash 'MathSetup'
-                                sh "echo CXX=${CLANG_CXX} -Werror > make/local"
-                                sh "echo STAN_THREADS=true >> make/local"
-                                sh "export STAN_NUM_THREADS=4"
-                                if (isBranch('develop') || isBranch('master')) {
-                                    runTests("test/unit")
-                                    sh "find . -name *_test.xml | xargs rm"
-                                } else {
-                                    runTests("test/unit -f thread")
-                                    sh "find . -name *_test.xml | xargs rm"
-                                    runTests("test/unit -f map_rect")
-                                    sh "find . -name *_test.xml | xargs rm"
-                                    runTests("test/unit -f reduce_sum")
-                                }
-                            }
-                        }
-                    }
-                    post { always { retry(3) { deleteDir() } } }
-                }
-            }
-        }
-
+       
         stage ('Discover changed distribution tests') {
             when {
                 expression {
@@ -490,7 +191,7 @@ pipeline {
                     if (params.runAllDistributions || isBranch('develop') || isBranch('master')) {
                         changedDistributionTests = sh(script:"python3 test/prob/getDependencies.py --pretend-all", returnStdout:true).trim().readLines()
                     } else {
-                        changedDistributionTests = sh(script:"python3 test/prob/getDependencies.py", returnStdout:true).trim().readLines()
+                        changedDistributionTests = sh(script:"python3 test/prob/getDependencies.py --pretend-all", returnStdout:true).trim().readLines()
                     }
                 }
             }
@@ -507,7 +208,7 @@ pipeline {
                     }
                 }
             }
-            agent { label 'linux && docker' }
+            agent { label 'linux && docker && 8core' }
             steps {
                 script {
                     def tests = [:]
@@ -547,24 +248,7 @@ pipeline {
             }
         }
 
-        stage('Upstream tests') {
-            agent { label 'linux' }
-            when {
-                allOf {
-                    expression {
-                        env.BRANCH_NAME ==~ /PR-\d+/
-                    }
-                    expression {
-                        !skipRemainingStages
-                    }
-                }
-            }
-            steps {
-                build(job: "Stan/Stan/${stan_pr()}",
-                        parameters: [string(name: 'math_pr', value: env.BRANCH_NAME),
-                                    string(name: 'cmdstan_pr', value: cmdstan_pr())])
-            }
-        }
+      
 
         stage('Upload doxygen') {
             agent {