Rough Idle When Cold

1. Defective ECU.
2. Open or shorted fuel injector circuit.
3. Stuck fuel injector.
4. Stuck air bypass valve in fast idle mechanism.
5. Open or shorted crank angle sensor circuit.
6. Defective crank angle sensor.
7. Open or shorted manifold air pressure sensor circuit.
8. Broken or disconnected manifold air pressure sensor hose.
9. Defective manifold air pressure sensor.
10. Open or shorted coolant temperature sensor circuit.
11. Defective coolant temperature sensor.
12. On High Altitude models, open or shorted atmospheric air pressure sensor circuit.
13. Defective EGR control system.