Why does my Audi A4 have a rough idle and how can I fix it?

When my Audi A4 is idling, I notice that the engine seems to shake or vibrate. It's not a smooth, consistent idle like it used to be. What could be causing this and is there a way to fix it?

First and foremost, it's important to check if your idle speed is within the manufacturer's recommended range. If it's too low, it can cause a rough idle. You may need to adjust the idle air control valve or clean the throttle body to improve idle speed and smoothness. Additionally, check for any vacuum leaks, as these can also affect idle quality.