Rough Idle

1. Defective ignition system.
2. Mechanical defect in engine.
3. Air intake system leaking.
4. Blockage in fuel system.
5. Defective pressure regulator.
6. Cold start injector leaking.
7. Defective supplementary air valve.
8. Defective air sensor.
9. Defective coolant temperature sensor.
10. Defective airflow meter.
11. Defective throttle position switch.
12. Incorrect idle speed adjustment.
13. Defective injectors.
14. Incorrect air bypass screw adjustment.
15. Bad connection in wiring harness or bad ground.
16. Defective electronic control unit.