When I hold the accelerater pedel at a constant the engine will rev to that speed but every few seconds it will drop about 100-200 rpm just for a half second and the go back to original rpm. This is a rebuilt 5.0 out of a 90 Bronco that only has about 5000 miles on it. Is this a problem or the starting of a problem?

 

Not 100% sure obviously, but one of the most common things is the TPS. Right underneath of the throttle body.

 

how expensive is a tps? working on a very limited budget.

 

not very at all...I don't remember off hand, but if I don't remember it, then it wasn't expensive. A limited budget is the only kind I know.

If you're still not sure, maybe hold of another day or two to get some more replies, but that part is one of the most common. Ever replaced it before? Do you know if it was done with the motor change? I know that mine wasn't, so maybe break out the receipts (if you didn't do the transplant yourself)

 

I got my TPS @ napa for around $35.00, easy to put on about a 15 min job. Sometimes they get dirty and you can take them off and clean them with some carb cleaner, you can try that as a $0.00 test.

 

Yeah, actually, I didn't mention that. Before I figured out it was my TPS (or was even sure what it was), I shot throttle body cleaner down the TB. While it didn't cure it, it helped out a lot.

 

On my 89, the fuel pressure regulator caused the exact thing. Do a search. there are numerous other things that can cause this and ways to correct them.

Good luck,