- Idle Air Control Valve (IAC) - The IAC valve controls the amount of air that bypasses the throttle plate when the engine is idling. If the IAC valve is dirty or faulty, it can cause the engine to rev up when starting and then shut off.
- Throttle Position Sensor (TPS) - The TPS tells the engine computer how much the throttle plate is open. If the TPS is faulty it can send the wrong signal to the computer which can cause the engine to rev up when starting and then shut off.
- Mass Air Flow (MAF) Sensor - The MAF sensor measures the amount of air flowing into the engine. If the MAF sensor is dirty or faulty it can send the wrong signal to the computer which can cause the engine to rev up when starting and then shut off.
- Vacuum Leak - A vacuum leak can cause the engine to run lean which can cause it to rev up when starting and then shut off.
- Fuel Pressure - Low fuel pressure can also cause the engine to run lean and rev up when starting and then shut off.
Here are some steps that you can take to try to resolve the problem:
1. Check the IAC valve and TPS. They should be clean and free of damage. If necessary clean the IAC valve with throttle body cleaner and replace the TPS.
2. Inspect the MAF sensor. Make sure it is not blocked by debris or damaged. Clean it with MAF sensor cleaner if necessary.
3. Check for vacuum leaks. Look for any disconnected or cracked hoses around the engine. Inspect the intake manifold gasket and valve cover gaskets for leaks as well.
4. Check fuel pressure. It should be between 40-45 psi. If it is low fuel pressure regulator could be faulty or the fuel pump may be failing.
If you are unable to resolve the problem you should take your Cougar to a qualified mechanic.
