I have a recently swapped engine from a 86' to a 87' body. Besides for a few problems, its able to start up but when you give it gas, it backfires and stalls. Any ideas that would cause this like the air/fuel mixture or the timing? The engine worked beautifully before the swap so the engine is in good shape.

 

check the AFM

 

The backfiring suggests it's too rich. If it is doing this while cold, I would look first at the AWS (water thermosensor) system.

If it does this after warmup, I would look at the AFM, TPS, MAP, and air temperature sensors.

I would also be inclined to: check for trouble codes; check the O2 sensor voltage as it backfires and stalls (verify it is a rich or lean condition)

Check timing, advance, and idle mixture, then set the TPS.

Double check that all the spark wires are hooked up correctly, i.e. no switched leads...

If none of that works, get down to the ECU connector and backprobe every pin and check the voltage against those published in the manual...

 

ok, Ill try that out and ill let you guys know what happens

 

I found the problem! It is running rich right now but I had a vacuum line that was disconnected. Thanks for the tips