96 3.8 running bad

[pyro1998]

My mustang idles fine but under normal to mild acceleration it misses after I push it harder it clears up. You can always feel a miss in it during driving. I have no codes in it, and the plugs, wires and coil pack have all been replaced during the motor rebuild. Any ideas

 

[Bullitt347]

There are so many things that could cause this condition. Diag over the internet is tough because I can not hear or see the car when the issue is happening. That being said.......re-check spark plug gap, is it correct? Are you sure? When was the last time the fuel injectors were cleaned? And not with something you just dumped into the gas tank. You can have the fuel injectors cleaned while still on the engine with a MotorVac. Otherwise, take them out and have them cleaned professionally. Any vacuum leaks? Have someone with a good scan tool that can data log watch fuel trims. The LTFT and STFT should not be correcting by more than 5% or so. If either is correcting by 10%+ then there is an issue that needs correcting. Try only one thing at a time or you will not know what made a change for the better or worse.

 

[pyro1998]

There are so many things that could cause this condition. Diag over the internet is tough because I can not hear or see the car when the issue is happening. That being said.......re-check spark plug gap, is it correct? Are you sure? When was the last time the fuel injectors were cleaned? And not with something you just dumped into the gas tank. You can have the fuel injectors cleaned while still on the engine with a MotorVac. Otherwise, take them out and have them cleaned professionally. Any vacuum leaks? Have someone with a good scan tool that can data log watch fuel trims. The LTFT and STFT should not be correcting by more than 5% or so. If either is correcting by 10%+ then there is an issue that needs correcting. Try only one thing at a time or you will not know what made a change for the better or worse.

Plugs are right, fuel injectors are new. I need to go thru and replace all vacuum lines. My scan tool will do the data log need to check that. Someone has said to clean the MAF so I'm going to try that Monday.