Engine Stalls Or Idles Rough

Check fuel system and control system pressure. Replace pressure regulator if necessary.
Check cold start valve for leaking (engine warm).
Ensure injector spray patterns and volume are correct. Replace faulty injectors.
Test coolant temperature sensor and wiring. Repair or replace as required.
Inspect intake air components for leaking hoses, connections or cracks. Repair as required.
Ensure airflow sensor plate movement and rest position. Adjust as necessary.
Test idle switch and idle air stabilizer valve.
Perform system electrical checks.
Check airflow meter. Replace if faulty.
Ensure idle RPM is correct.
Check auxiliary air by-pass regulator.
Check fuel injector electrical connections.
Use stethoscope to verify fuel injectors are operating.
Ensure sufficient secondary spark is available in all cylinders.
Verify vacuum hose routing is correct and there are no vacuum leaks.
Check idle stabilizer operation.
Check for EGR system malfunction (if equipped).
Check O2 sensor operation.
Check for distortion or cracks in fuel injector(s) plastic connecting flange(s).
Check for use of poor quality fuel containing insufficient cleaning additives. Prolonged use of poor quality fuel can cause injector clogging and carbon build-up on intake system.