diff --git a/tests/IronPython.Tests/Cases/CommonCases.cs b/tests/IronPython.Tests/Cases/CommonCases.cs
index d8d5ac163..b8bd7d6c3 100644
--- a/tests/IronPython.Tests/Cases/CommonCases.cs
+++ b/tests/IronPython.Tests/Cases/CommonCases.cs
@@ -3,7 +3,6 @@
 // See the LICENSE file in the project root for more information.
 
 using System;
-using System.IO;
 using System.Threading;
 
 using NUnit.Framework;
@@ -37,42 +36,6 @@ protected int TestImpl(TestInfo testcase) {
                 return -1;
             } finally {
                 m?.ReleaseMutex();
-                CleanupTempFiles(testcase);
-            }
-        }
-
-        /// <summary>
-        /// Removes @test_*_tmp files/directories left behind by test.support.TESTFN.
-        /// </summary>
-        private static void CleanupTempFiles(TestInfo testcase) {
-            var testDir = Path.GetDirectoryName(testcase.Path);
-            if (testDir is null) return;
-
-            // Clean test directory and also the StdLib test directory
-            CleanupTempFilesInDir(testDir);
-            var stdlibTestDir = Path.Combine(CaseExecuter.FindRoot(), "src", "core", "IronPython.StdLib", "lib", "test");
-            if (stdlibTestDir != testDir) {
-                CleanupTempFilesInDir(stdlibTestDir);
-            }
-        }
-
-        private static void CleanupTempFilesInDir(string dir) {
-            if (!Directory.Exists(dir)) return;
-
-            try {
-                foreach (var entry in Directory.EnumerateFileSystemEntries(dir, "@test_*_tmp*")) {
-                    try {
-                        if (File.GetAttributes(entry).HasFlag(FileAttributes.Directory)) {
-                            Directory.Delete(entry, recursive: true);
-                        } else {
-                            File.Delete(entry);
-                        }
-                    } catch {
-                        // ignore locked/in-use files
-                    }
-                }
-            } catch {
-                // ignore enumeration errors
             }
         }
     }
diff --git a/tests/IronPython.Tests/Cases/IronPythonCasesManifest.ini b/tests/IronPython.Tests/Cases/IronPythonCasesManifest.ini
index c6106d718..07fe270f8 100644
--- a/tests/IronPython.Tests/Cases/IronPythonCasesManifest.ini
+++ b/tests/IronPython.Tests/Cases/IronPythonCasesManifest.ini
@@ -4,9 +4,6 @@ WorkingDirectory=$(TEST_FILE_DIR)
 Redirect=false
 Timeout=120000 # 2 minute timeout
 
-[IronPython.test_async]
-IsolationLevel=PROCESS # loads IronPythonTest assembly, causes a failure in IronPython.test_attrinjector
-
 [IronPython.test_builtin_stdlib]
 RunCondition=NOT $(IS_MONO)
 Reason=Exception on adding DocTestSuite
diff --git a/tests/suite/test_async.py b/tests/suite/test_async.py
index 93236db82..59ae3500a 100644
--- a/tests/suite/test_async.py
+++ b/tests/suite/test_async.py
@@ -6,7 +6,8 @@
 
 import unittest
 
-from iptest import run_test
+from iptest import run_test, skipUnlessIronPython, is_netcoreapp
+from iptest.ipunittest import load_ironpython_test
 
 
 def run_coro(coro):
@@ -319,6 +320,7 @@ async def test():
         self.assertEqual(run_coro(test()), ['enter', 1, 2, 'exit'])
 
 
+@skipUnlessIronPython()
 class DotNetAsyncInteropTest(unittest.TestCase):
     """Tests for .NET async interop (await Task, async for IAsyncEnumerable, CancelledError)."""
 
@@ -423,6 +425,9 @@ def test_cancellation_token_cancel(self):
         cts.Cancel()
         self.assertTrue(token.IsCancellationRequested)
 
+
+@unittest.skipUnless(is_netcoreapp, "ValueTask is not available on .NET Framework")
+class ValueTaskInteropTest(unittest.TestCase):
     def test_await_valuetask(self):
         """await a ValueTask (non-generic)."""
         from System.Threading.Tasks import ValueTask
@@ -464,8 +469,8 @@ async def test():
 import sys
 if sys.implementation.name == 'ironpython':
     import clr
+    load_ironpython_test()
     try:
-        clr.AddReference('IronPythonTest')
         from IronPythonTest import AsyncInteropHelpers
         _has_async_helpers = True
     except Exception: