1993 gt, when i get around 4000 rpm it misses out really bad, i changed the plugs, cap and rotor, could this be the fule pump? or maybe sidtributor? any help you could give would be great!oh it misses out when you are driving and also doea it if you are in nuetral and just rev it up
Things that could cause you problem include a bad fuel pressure regulator, timing/distributor, bad coil and mabye a bad fuel pump. I am not extremly familiar with the fuel injected engines but those are the thing I think you should take a look at. I really don't think it is a bad fuel pump that is causing your problem. You should try reading the fault codes off your mustang's computer. Sometimes they will tell you what is wrong.
High speed miss under load is usually ignition related.
Since you have changed the plugs, & distributor cap, either the spark plug wires or TFI module are the likely culprit.
Wait until dark and do the "Do I see sparks test". Open the hood and start the car. Watch the plug wires for spark jumping or glowing around the boots along the wires. If you have an automatic, have someone run the engine up against the brakes and do the test. Just be careful that they don't give it too much throttle or let up on the brake. If you have access to an Volt/Ohm meter, check the resistance of the wires. They should be about 2000 ohms or less per foot of lenght.
The TFI module is mounted on the distributor on 86-93 year cars. When you know for sure that the cap, plug wires and plugs are good, it is the most likely source of a high speed miss.
Get the codes pulled and that should tell you if you have anything amiss. You can take the TFI module to autozone and they can check it for you. And if its bad go the ford dealer and get one from them, the autoparts store brands are cheap and don't last.
Here's the link to dump the computer codes with only a jumper wire or paper clip and the check engine light, or test light or voltmeter. I’ve used it for years, and it works great.