* Idle Air Control (IAC) Valve: This valve regulates air flow at idle. A dirty or faulty IAC valve can cause the engine to stall, especially when the engine is under load (like when the car is stopped with accessories on).
* Throttle Position Sensor (TPS): The TPS tells the computer the throttle's position. A faulty TPS can send incorrect information, leading to erratic idle and stalling.
* Mass Airflow Sensor (MAF) Sensor: This sensor measures the amount of air entering the engine. A dirty or faulty MAF sensor can cause a lean fuel mixture, resulting in stalling.
* Fuel System Issues: A weak fuel pump, clogged fuel filter, or problems with the fuel injectors can restrict fuel delivery, causing the engine to stall when it's idling and under increased demand from accessories.
* Vacuum Leaks: Leaks in the vacuum system can disrupt the proper air/fuel mixture, affecting the idle and potentially causing stalling.
* PCV Valve: A clogged Positive Crankcase Ventilation (PCV) valve can create excessive crankcase pressure, affecting the engine's performance and leading to stalling.
* Spark Plugs and Wires: Worn spark plugs or damaged ignition wires can cause misfires, especially noticeable at idle when the engine is under stress.
* Battery/Alternator: A weak battery or alternator failing to charge the battery adequately can cause voltage drops, leading to stalling. This is more likely if other electrical components are running (e.g., air conditioning).
* Transmission Issues (Less Likely): While less common, transmission problems can sometimes cause stalling, though usually accompanied by other symptoms.
Troubleshooting Steps:
It's impossible to diagnose the exact problem remotely. To find the cause, you should:
1. Check the obvious: Make sure the battery terminals are clean and tight.
2. Inspect the engine bay: Look for any visible vacuum leaks or loose connections.
3. Consult a repair manual: A repair manual specific to your 2000 Chevrolet Impala will provide detailed information on troubleshooting these systems.
4. Use a code reader (OBDII scanner): A code reader can detect any trouble codes stored by the car's computer, which might point to the problem area.
5. Take it to a mechanic: If you're not comfortable working on your car yourself, taking it to a qualified mechanic is the best option. They have the tools and experience to diagnose and repair the problem efficiently.
The stalling at red lights strongly suggests a problem with the idle system or fuel delivery. Addressing these areas first is likely to yield the best results.
