Car is running real bad

I hope someone can help me here because I am out of ideas on our car. Our stang has 129K on it and here is what is going on. The car had an intermittent rough idle that has become real bad almost like the car is ready to die. The new parts include plug wires, plugs, cap, O2's , all new vacuum lines, IAC, Mass air meter cleaned new fuel filter, new coil. I have changed out the TFI module with a known good one and it had no affect, also I have inspected the engine bay up and down and replaced all vacuum lines with no luck.


I am out of ideas and I don't want to take it to our local Ford dealer because of previous dealings with them. Could it be the PIP sensor or fuel pump? I have a fuel pressure guage and there is a slight fluctuation in fuel pressure but nothing to bad. Sitting in the car and watching the tach it will drop 100 rpms instantly when it misfires.


Help Thanks in advance.

I've done KOEO and KOER testing on it and came up empty on codes, as far as it acting up it used to be a random thing but now it is doing alot more frequently cold or hot.


Thanks

Fixed it, problem was the gasket between the upper and lower intake. An hours worth of work and it idles smooth as silk, hell it is better than its ever been.


:SNSign:

HISSIN50 said:

I'm glad you got that one figured out - in all honestly, it would have been *way* down on my mental list of things it could be.

I won't even ask how you knew that was it. I do have kind of a cool test for testing the plenum and intake seal in general but it's a PITA to do.

Click to expand...

I've seen this before on my 5.0 powered F-150 is how I new about checking for that