Unstable Idle
- Check for intake air leaks.
- Check Positive Crankcase Ventilation (PCV) system.
- Check Exhaust Gas Recirculation (EGR) system.
- Check idle speed adjustment.
- Check idle adjustment screw passage for clogging.
- Check Idle Air Control (IAC) Valve.
- Check fuel pressure.
- Check fuel injectors.
- Check ignition spark and spark plugs.
- Check Heated Oxygen Sensor (HO2S).
- Check engine mechanical condition.