mysticowner

We have a 90 GT that we rebuilt 3 years ago. This year it started having an issue. When it's cold the engine is snappy as heck like it allways was.

As it warms up it gets worse and worse. To the point when you push on the gas she goes slower.
There is about 5,000 miles on it.

We went over the salt and pepper shakers, all connections replaced the TPS and cleaned the mass air. It's a pro 5.0. I'm at the point where I believe the computer may be the issue.

The air fuel meter reads lean while warming up and is clear off the scale when it warms up a bit. In the early warm up blip the gas and the air fuel meter reads but warmed up it's gone. I have a switch on one meter to read both sides. They are the same.

I checked vacuum hoses etc, it has an edelbrock intake and throttle body, 24lb injectors, long tube headers, comp cams cam,edelbrock heads, probe pistons, It ran great for 3 years something happened. I also changed the sensor that is in the water pipe... can't remember the name right now.

Timing is right on and advance works 35 total. complete msd ignition with a 6 al box. I have another box and plan on trying that but haven't had time yet.

Fuel pressure is 36 and 41 when you lay on it.

Vacuum is around 22 going down hill backing off, when we had an intake leak with the old motor it was around 14.

I'd hate to buy a computer and find out that's not it. What do you guys think?

Mustangs4U

Welcome to the forum. I am sure there is someone here that can help.

Good luck with the issue.

mysticowner

That's what I thought. It's like chasing a ghost but we will find it. Hopefully before
throwing a bunch of parts at it.

eb2gt

could the coil be breaking down as it gets warm? Think about that and see.

mysticowner

I dont think the coil even has time to get warm when this starts happening. Also the air fuel meter goes clear off scale, I don't think it would do that if the coil were breaking down would it??