* Idle Air Control (IAC) Sensor Issues (even after cleaning): While you cleaned it, it might still be faulty. The IAC is a crucial component for controlling idle speed. A malfunctioning IAC, even after cleaning, can cause stalling, especially at idle. Consider replacing it entirely, as cleaning doesn't always resolve internal issues.
* Throttle Position Sensor (TPS): This sensor tells the engine's computer the throttle's position. A faulty TPS can lead to erratic idling and stalling. It needs testing with a multimeter to determine if it's within specification.
* Mass Airflow Sensor (MAF) Sensor: (If equipped) This sensor measures the amount of air entering the engine. A dirty or faulty MAF sensor can cause incorrect fuel mixture calculations, resulting in stalling. Cleaning the MAF sensor (with MAF sensor cleaner only – *never* brake cleaner) is worth trying, but replacement may be necessary.
* Vacuum Leaks: A small vacuum leak in the intake manifold, hoses, or other parts of the intake system can significantly affect idle. Carefully inspect all vacuum lines and connections for cracks, holes, or loose fittings. Use a vacuum gauge to verify proper manifold vacuum at idle if you suspect a leak.
* Fuel Pressure Regulator: A failing fuel pressure regulator could cause inconsistent fuel delivery, leading to stalling, particularly at idle when fuel demand is low. Testing fuel pressure is necessary to diagnose this.
* Ignition System: Weak spark, faulty ignition coil, or a problem with the distributor (if equipped) can cause the engine to die at idle when the engine's demands are low. Check the ignition system components.
* Clogged Catalytic Converter: A severely clogged catalytic converter can restrict exhaust flow, putting a strain on the engine and leading to stalling. This is less likely to be the immediate cause if the engine runs fine at higher RPMs.
Troubleshooting Steps:
1. Retest the IAC Sensor: Even after cleaning, it's possible it's still bad. A replacement is relatively inexpensive.
2. Check for Vacuum Leaks: This is a common issue and relatively easy to check.
3. Test the TPS and MAF Sensor (if applicable): These require a multimeter and a knowledge of the proper testing procedures. A Haynes or Chilton repair manual for your specific vehicle will provide these procedures.
4. Test Fuel Pressure: This requires a fuel pressure gauge and adapter. Low or inconsistent fuel pressure points to a fuel system problem.
5. Inspect the Ignition System: Check the spark plug wires, distributor cap, rotor, and ignition coil for any signs of damage or wear.
Recommendation: Start with the relatively inexpensive and easy checks – vacuum leaks and a replacement IAC sensor. If the problem persists, you'll need to move on to testing the other components, potentially requiring a multimeter and specialized tools. Consider consulting a mechanic if you're uncomfortable performing these tests yourself.
