How to troubleshoot sudden engine misfires in an Audi 80?

I've been experiencing occasional engine misfires on my Audi 80, without any warning signs or symptoms before. How can I properly troubleshoot and diagnose the root cause of this problem?

Check your spark plugs and ignition coils to see if any of them are faulty or worn out. A faulty spark plug can cause intermittent engine misfires and should be replaced immediately.

Inspect your fuel pressure regulator to ensure it is properly regulating the fuel in your engine. An improperly functioning regulator can lead to sudden engine misfires.