Fuel System:
* Crankshaft Position Sensor (CKP): This sensor is crucial for the engine's timing. A faulty CKP can cause the engine to stall, especially when idling or under low load (like when you stop). The engine might crank but not start afterwards if this is the issue.
* Cam Position Sensor (CMP): Similar to the CKP, a failing CMP will disrupt the engine's timing and lead to stalling.
* Fuel Pump: A weak fuel pump might provide sufficient pressure at higher RPMs (while driving), but struggle to maintain it at idle. The engine starves for fuel and dies. Listen carefully for the fuel pump's whine when you turn the key to the "on" position (before cranking). A weak or failing pump might make a weak sound or not be heard at all.
* Fuel Filter: A clogged fuel filter restricts fuel flow, leading to similar symptoms to a weak pump. This is a relatively inexpensive and easy component to replace.
* Fuel Pressure Regulator: This regulates fuel pressure in the system. A faulty regulator can cause inconsistent fuel delivery.
Ignition System:
* Ignition Coil: A failing ignition coil can intermittently lose spark, causing the engine to stall.
* Distributor (if equipped): Older vehicles may have distributors. Issues with the distributor cap, rotor, or ignition module can lead to intermittent spark loss. (Less likely on a 1997, but possible).
* Ignition Switch: A failing ignition switch may not provide consistent power to the ignition system, causing the engine to stall.
Other Potential Problems:
* Idle Air Control (IAC) Valve: This valve regulates air flow at idle. A dirty or malfunctioning IAC valve can cause erratic idling and stalling. Cleaning it is often a simple first step.
* Mass Airflow Sensor (MAF): A faulty MAF sensor provides inaccurate readings of the air entering the engine, leading to poor fuel mixture and potential stalling.
* Throttle Position Sensor (TPS): Provides the engine computer with information about throttle position. A faulty sensor can cause erratic idling and stalling.
* Computer (PCM): While less common, a failing PCM (Powertrain Control Module) can cause a wide range of problems, including stalling. Diagnosing this requires specialized equipment.
* Vacuum Leaks: A vacuum leak in the intake system can disrupt the air/fuel mixture, leading to stalling.
Troubleshooting Steps:
1. Check for Diagnostic Trouble Codes (DTCs): Use an OBD-II scanner to retrieve any stored trouble codes. This is the *first* thing you should do. The codes will often directly point you to the faulty component.
2. Listen for the Fuel Pump: As mentioned above, listen for the pump's whine when you turn the key to the "on" position.
3. Check the IAC Valve: Clean the IAC valve with appropriate cleaner (follow instructions carefully).
4. Inspect Vacuum Hoses: Look for any cracked, loose, or disconnected vacuum hoses.
5. Consider the Age of Parts: Given the age of the vehicle, many components might be nearing the end of their lifespan. Consider preventative maintenance replacing items like the fuel filter.
It's difficult to pinpoint the exact cause without further diagnostics, but addressing the fuel system and ignition system components is the most logical starting point. Get an OBD-II scanner to read any trouble codes – they're your best starting point. If you're not comfortable working on your vehicle yourself, take it to a qualified mechanic for diagnosis and repair.
