High-Probability Causes:
* Crankshaft Position Sensor (CKP Sensor): This sensor tells the computer the engine's rotational speed. A failing CKP sensor will cause the engine to stall unpredictably. The intermittent nature of the problem strongly suggests this. It's relatively inexpensive to replace.
* Fuel Pump/Fuel Delivery Issues: The fuel pump might be failing intermittently, unable to maintain sufficient pressure. This could lead to stalling, especially under load (going uphill or accelerating). A clogged fuel filter could also contribute. A mechanic can test fuel pressure.
* Ignition System Problems: This could include a failing ignition coil, distributor cap, rotor, or spark plug wires. These components wear out over time, and intermittent failure would cause stalling. A visual inspection of these components is a good starting point.
* Mass Airflow Sensor (MAF Sensor): This sensor measures the amount of air entering the engine. A faulty MAF sensor can cause erratic fuel delivery, leading to stalling.
Less Likely, but Still Possible Causes:
* Computer/ECU Problems: While less likely, a failing Engine Control Unit (ECU) can cause unpredictable issues. This is a more involved diagnosis and repair.
* Wiring Issues: Corrosion, damaged insulation, or loose connections in the wiring harness can cause intermittent electrical problems, impacting the fuel system, ignition system, or sensors.
* Alternator: Although less likely to cause immediate stalling, a failing alternator might not be charging the battery adequately. If the battery is low, the car might stall. Test the alternator's output voltage.
* Throttle Position Sensor (TPS): A faulty TPS can lead to improper fuel mixture and stalling, but this is less likely to be the sole cause of the intermittent behavior.
Troubleshooting Steps:
1. Check the obvious: Look for any loose or damaged wiring, especially around the engine. Check the battery connections for corrosion and tightness.
2. Have a mechanic check fuel pressure: This will rule out fuel pump issues.
3. Have a mechanic test the crankshaft position sensor (CKP): This is likely a top suspect.
4. Have a mechanic test the MAF sensor: This sensor is relatively easy to test.
5. Inspect the ignition system: Visually inspect the distributor cap, rotor, spark plug wires, and ignition coil for cracks, damage, or excessive wear.
6. Consider a diagnostic scan: A mechanic can use an OBD-II scanner (although your 1992 car might not have a fully standard OBD-II port) to read any trouble codes stored in the ECU. This might give you more clues.
Important Note: Because the car sometimes restarts automatically, this points towards an intermittent electrical fault. This makes thorough electrical testing crucial. Don't attempt major repairs yourself unless you have significant experience with automotive electrical systems. A mechanic with experience working on older vehicles will be best equipped to diagnose this problem accurately.
