1. Idle Air Control (IAC) Valve: This is a very common cause. The IAC valve regulates the air entering the engine at idle. If it's dirty, sticking, or failing, the engine won't get enough air to maintain idle speed and will stall.
* Troubleshooting: Inspect the IAC valve for cleanliness. You might be able to clean it with carb cleaner (be careful with electronics!), but often replacement is the better solution.
2. Throttle Position Sensor (TPS): The TPS tells the computer the throttle's position. A faulty TPS can give incorrect signals, leading to poor idle and stalling.
* Troubleshooting: This usually requires a multimeter to check its voltage output at different throttle positions. A bad reading indicates a faulty sensor requiring replacement.
3. Vacuum Leaks: Vacuum leaks disrupt the proper air/fuel mixture. Cracked vacuum hoses, a leaking intake manifold gasket, or a problem with the carburetor (if equipped) can cause stalling.
* Troubleshooting: Visually inspect all vacuum lines for cracks or damage. Listen for hissing sounds near the intake manifold while the engine is running (use caution). A smoke test can help pinpoint leaks.
4. Fuel Delivery Problems: While less likely to cause stalling *only* at stops, issues with the fuel pump, fuel filter, or clogged carburetor jets can lead to a lack of fuel at low engine speeds.
* Troubleshooting: Check fuel pressure (requires a gauge). Inspect the fuel filter for blockage. If you have a carburetor, it might need cleaning or rebuilding.
5. Distributor/Ignition System (if applicable): A failing distributor cap, rotor, wires, or coil can cause intermittent misfires, leading to stalling. This is more likely if the stalling is accompanied by other symptoms like rough running or misfires.
* Troubleshooting: Inspect the distributor cap and rotor for cracks or wear. Check the ignition wires for damage or loose connections.
6. Engine Temperature: Sometimes, a problem only arises when the engine is fully warmed up. This could point to issues with the cooling system affecting the mixture or other temperature-sensitive components.
Troubleshooting Steps:
1. Start with the easiest: Check for obvious vacuum leaks and clean the IAC valve.
2. Check engine codes: If your van has a check engine light, get the codes read using an OBD scanner (if equipped, older models might not be).
3. Systematic approach: Work through the potential causes listed above, one by one, checking and testing as you go.
4. Professional help: If you're not comfortable working on your vehicle's systems, take it to a qualified mechanic. They have the tools and expertise to diagnose the problem accurately.
Remember safety first! Work on a cool engine and disconnect the battery negative terminal before working on any electrical components.
