Why does my Audi A4 lose power while idling?

My Audi A4 seems to lose power and shake while idling, but it runs smoothly while driving. What could be causing this issue?

This could be due to a faulty oxygen sensor. It's important to have this checked and replaced if necessary, as it can affect your engine's performance and fuel efficiency.

Another potential cause could be a clogged fuel filter. This can restrict the flow of fuel to your engine, leading to issues with idling and overall performance. Consider getting it replaced.