95 4.3l to a 305 out of a 91 Firebird...4.3l PCM has no injector pulse so I switched to a 350 Tahoe PCM giving me my injector pulse along with a really large problem... I can't rev over 3 grand in gear with out it blowing the I/P cluster fuse and eliminating my charging circuit...I was under the impression I would not have to have the PCM flashed...Is this not the case....It will rev to the moon not in gear...Smile upon me Blazer Gods

 

You need to get a custom tune on the PCM, no ifs, ands or buts about it.