How to troubleshoot faulty spark plugs in an Audi 80?

I have been experiencing misfires and rough engine idle in my Audi 80. I suspect it might be due to faulty spark plugs. How can I diagnose and resolve this issue?

First, use a spark plug tester or multimeter to check for any signs of wear or damage on the spark plugs. If they are worn out, it's time to replace them. Additionally, make sure the spark plugs are gapped correctly for your specific Audi 80 model.