I am having some trouble figuring this one out 100%. I have just recently swapped engines in my 1989 gt cobra (Ford Mustang). The engine that was in it was a 5.0l HO V8, but the engine that I have just recently put in it is just a regular 5.0l v8. I bring this up because I believe that my problem may have something to do with the computer that is in the car. Everything, mechanically, is done and is 100%.

My car is idleing very well, steady at about 800 RPM's. But as soon as I engage my transmission into reverse or into drive, the car will either stall while sitting there, or whenever I go to give it some gas. I have checked all of my vacuum lines, and I even re-checked my timing, but everything is at its full potential. I believe my problem may be consistent with my computer, but the electronics are my weak point, can anyone give me some help with this one?
Thanks,
Cobra1967

I believe your diagnosis is correct. You may need to change the PCM, wiring harness, etc. for your new engine. Electrical system compatibility is often initially overlooked on engine/transmission swaps.