* Fuel Delivery Problems:
* Fuel Pump Failure: The fuel pump is the most common suspect. If it's failing, it might be providing insufficient fuel pressure at higher engine speeds and under load, causing the engine to starve for fuel and stall. This is especially likely if it only happens at highway speeds.
* Clogged Fuel Filter: A restricted fuel filter prevents enough fuel from reaching the engine.
* Fuel Injectors: Clogged or failing fuel injectors can prevent proper fuel delivery. This might manifest more at higher RPMs.
* Fuel Pressure Regulator: A faulty regulator might not maintain the correct fuel pressure.
* Ignition System Issues:
* Distributor Cap and Rotor: Worn or damaged components in the distributor can lead to misfires and stalling, especially under load.
* Ignition Coil: A failing coil might not generate enough spark at higher speeds.
* Spark Plug Wires: Damaged or worn spark plug wires can cause misfires.
* Ignition Module (TFI Module): A common point of failure in these Mustangs. The TFI module controls the ignition timing and a malfunction can cause intermittent or complete engine failure.
* Electrical Problems:
* Alternator: While unlikely to cause an immediate stall, a failing alternator could lead to a voltage drop, causing the ignition system or fuel pump to malfunction. You might notice other electrical issues before the stall.
* Wiring Issues: Corrosion, loose connections, or damaged wiring harnesses can interrupt the flow of electricity to critical components.
* Computer (EEC-IV): Although less common, a failing computer can cause erratic engine behavior, including stalling.
* Other Possibilities (Less Likely but Worth Considering):
* Vacuum Leaks: Severe vacuum leaks can disrupt engine operation and lead to stalling.
* Throttle Position Sensor (TPS): A faulty TPS can provide incorrect information to the computer, resulting in poor engine management.
Troubleshooting Steps:
Since this is a safety-critical issue, don't attempt to drive the car until it's fixed. Have it towed to a mechanic or work on it in a safe environment. Diagnosing this requires a systematic approach:
1. Check for obvious signs: Look for any obvious fuel leaks, damaged wiring, or loose connections.
2. Check fuel pressure: A mechanic needs a fuel pressure gauge to test the fuel system.
3. Test the ignition system: Check the distributor cap, rotor, spark plugs, wires, and coil.
4. Inspect the TFI module: This is a common failure point.
5. Scan the computer (EEC-IV): A code reader can pull diagnostic trouble codes from the car's computer, providing valuable clues.
Because multiple systems are involved, it's best to get a qualified mechanic to diagnose the problem. Attempting repairs without proper knowledge can be dangerous and may not fix the underlying issue.
