How do I troubleshoot an engine misfire in my Audi A3?

I've noticed my Audi A3 has been experiencing a rough idle and decreased engine performance. What steps can I take to diagnose and fix the issue?

First, check your spark plugs and ignition coils to see if they need to be replaced. If not, it could be a problem with your fuel injection system. Have a mechanic check the fuel filter and fuel pressure regulator.

Another possibility is a vacuum leak, which can cause a misfire. Check all vacuum hoses and connections for any cracks or leaks, and replace if necessary.