5.0 conversion HELP
 

I recently installed a 1988 5.0 into a 1975 Bronco. The engine ran excellent in the car. After making all of the wiring modifications and the balancing swaps it fired. It continues to run good, however it acts like it has a huge vacuum leak. One second it wil idle great, the next it will miss and stutter like it has an ignition problem. I can't find a vacuum leak anywhere and it is too inconsistant to make me belive that it has one. I'm kinda stumped. It runs great at higher rpms, but it tries to fall on its face and stutter when I put it into gear at idle. Is there a sensor that will make it act like this. I had to use the MAP system until I find a MAF computer. Will a bad MAP make it run irratic? Any help is good help. As far as modifications, the EGR has been removed, the sensor in the cooling lines was moved to the back of the intake, the cooling lines going through the throttlebody were removed, and thats about it. Please help

I don't really know what to say about your problem but from what I heard the egr is vital to your engine running correctly because it is part of the whole system that the computer works through.

Thank you for the heads up. I reinstalled the egr and the electronics. Its a little better until I connect the vacuum to the egr valve. As soon as you do this, it dies.?? There was one other sensor in the cooling tubes that was removed and relocated to the rear of the manifold where the coolin nipple for the throttlebody used to be. I will connect that tonight and see what happens. Thank you..

There's also an EGR position sensor on the back of the EGR - made my engine die at cold start and idle very rough when warm. Had same symptons another time when the EGR was sticking and wouldn't open. Last, take off your idle air speed motor/valve and clean the carbon out of the valve at the seat. Don't use a metal tool and try to scrape it, soak it with i.e. carb spray, then use a tiny brush / an air compressor, etc. Also make sure that the IAS motor is functioning.

PS - Any of those parts are fairly easy to remove/replace. One simple way to tell if any particular thing is bad is to swap it with a known good part off another similar engine (if you've got any good buddies with a 5.0?) cheaper than guessing - some of those parts are expensive, and even a code reader doesn't narrow it down all the way.