1. Vacuum leak: A vacuum leak can cause the engine to run lean, which can lead to rough idling. Check all of the vacuum hoses and connections for any cracks or leaks.
2. Fuel injector: A faulty fuel injector can cause the engine to run rich or lean, which can lead to rough idling. Try cleaning the fuel injectors and see if that makes a difference.
3. Throttle body: A dirty throttle body can cause the engine to idle rough. Try cleaning the throttle body and see if that makes a difference.
4. Spark plugs: Worn or fouled spark plugs can cause the engine to run rough. Try replacing the spark plugs and see if that makes a difference.
5. Ignition coil: A faulty ignition coil can cause the engine to run rough. Try replacing the ignition coil and see if that makes a difference.
6. PCV valve: A faulty PCV valve can cause the engine to run rough. Try replacing the PCV valve and see if that makes a difference.
7. EGR valve: A faulty EGR valve can cause the engine to run rough. Try cleaning the EGR valve and see if that makes a difference.
8. Camshaft position sensor: A faulty camshaft position sensor can cause the engine to run rough. Try replacing the camshaft position sensor and see if that makes a difference.
If you have checked all of these things and the engine is still idling rough, you may need to take it to a mechanic for further diagnosis.
