What is causing the rough idling in my 1992 Audi 80?

My Audi 80 has been idling rough for the past week. It seems to shake and vibrate a lot more than usual, especially when stopped at a red light. I've checked the spark plugs and air filter, but they appear to be in good condition. What could be the cause of this issue?

It's possible that your fuel injectors are clogged. This can cause a rough idle and can be fixed by using a fuel injector cleaner. Try adding one to your next tank of gas.