* Idle Air Control (IAC) Valve: This valve regulates the air entering the engine at idle. A dirty or malfunctioning IAC valve can cause the engine to stall, especially when idling or at low speeds. It's a relatively easy part to clean or replace.
* Throttle Position Sensor (TPS): This sensor tells the engine control unit (ECU) the position of your throttle. A faulty TPS can provide incorrect information, leading to erratic idling and stalling.
* Crankshaft Position Sensor (CKP): This sensor tells the ECU the position of the crankshaft. A failing CKP can cause misfires and stalling, particularly when the engine is under low load (like idling).
* Mass Airflow Sensor (MAF): This sensor measures the amount of air entering the engine. A dirty or faulty MAF sensor can cause the engine to run lean, leading to stalling. Cleaning it (carefully, following instructions) is often the first step.
* Fuel Pressure Regulator: While less likely given it runs when you accelerate, a failing fuel pressure regulator could cause inconsistent fuel pressure, leading to stalling at idle.
* Vacuum Leaks: Small vacuum leaks in hoses or the intake manifold can disrupt the air-fuel mixture, causing erratic idling and stalling. Inspect all vacuum lines for cracks or disconnections.
Troubleshooting Steps (in order of ease):
1. Check for Vacuum Leaks: Visually inspect all vacuum lines for cracks or loose connections. Listen carefully around the intake manifold while the engine is running for hissing sounds that might indicate a leak.
2. Clean the IAC Valve: This is often the easiest and cheapest fix. Locate the IAC valve (usually on the throttle body) and clean it with throttle body cleaner. Make sure to follow the cleaner's instructions carefully.
3. Check the TPS: You'll likely need a multimeter to test the TPS voltage output. There are many online tutorials showing how to test a TPS for a 1990 LeBaron. A faulty reading points to a replacement being needed.
4. Clean the MAF Sensor: Carefully clean the MAF sensor with MAF sensor cleaner (never use anything else). Be gentle, as the sensor is delicate.
Important Considerations:
* Your car is 30+ years old. Many other components could be contributing to the problem, and multiple issues might be present.
* Safety First: If your car is stalling dangerously while driving, have it towed to a mechanic. Driving a car that stalls unpredictably is risky.
* Mechanic: If you're not comfortable working on your car, take it to a qualified mechanic. They have the tools and expertise to diagnose the problem accurately and efficiently. Mention the symptoms (stalls at low speeds, runs fine when accelerating).
Start with the easiest and cheapest options (vacuum check and cleaning the IAC and MAF). If that doesn't solve the problem, you'll likely need more advanced diagnostics or professional help. Good luck!
