2. Check the fuel filter. A clogged fuel filter can restrict fuel flow to the engine, causing it to run lean and idle roughly.
3. Check the spark plugs. Worn-out spark plugs can cause the engine to misfire, which can lead to a rough idle.
4. Check the spark plug wires. Damaged spark plug wires can cause the engine to misfire, which can lead to a rough idle.
5. Check the PCV valve. A stuck PCV valve can cause the engine to run rich and idle roughly.
6. Check the throttle body. A dirty throttle body can cause the engine to idle roughly.
7. Check the IAC valve. A faulty IAC valve can cause the engine to idle too high or too low.
8. Check the fuel pressure. Low fuel pressure can cause the engine to run lean and idle roughly.
9. Check the vacuum lines. A vacuum leak can cause the engine to run lean and idle roughly.
