I took a cache clearer from the O.G Spintires, and changed some of the code so it works for mudrunner. Use at your own risk.
https://drive.google.com/open?id=1OeBgVfSGEeq7AMLlK9wk-xBlN7zUrBD7
Put this in the mudrunner directory, and run.
Command Prompt Will run, and ask if you want to delete the mudrunner appdata. (which is what clearing cache does)
Press 'Y' And you're done