Symptom Definition

Engine starts but will not run at idle. Engine runs if accelerator is held at part throttle.

Possible Causes & Corrections: 

• Problem is most likely in Idle Air Control (IAC) system. See DIAGNOSTIC AIDS in DTC 35 chart in appropriate TESTS W/CODES article in the ENGINE PERFORMANCE section below.
• TESTS W/CODES - 4.3L
• TESTS W/CODES - 5.0L
• TESTS W/CODES - 5.7L
• TESTS W/CODES - 7.4L
• Check EGR system.
• Check park/neutral switch.
• Disconnect MAP sensor. If condition is corrected, replace sensor.