How do I troubleshoot a malfunctioning Audi A4 engine?

I'm experiencing issues with my Audi A4 engine and I'm not sure where to start with troubleshooting. Any tips or advice would be greatly appreciated.

Check your spark plugs and ignition coils first. These are a common cause of engine malfunction in Audi A4s. If they seem fine, then move onto checking the fuel system.

Make sure your air filters are clean and free of debris. Clogged air filters can greatly affect engine performance on Audi A4s. Also, check for any vacuum leaks as these can cause issues as well.

If you're still having trouble, it might be a more serious issue such as a faulty sensor or wiring problem. It's best to take it to a certified Audi mechanic for a thorough diagnosis.