ok heres the deal the tranny in my 91 305 firebird blew 3rd and 4th i need a tranny quick and didnt have much money so i went to the junk yard and pulled one out of a 89 tbi v8 truck to fine out the tranny is an 83 and was missing the wireing in the tranny but has the 732 pump. i used the old converter and wiring w sensors and bolted the tranny in but now the car sounds like its under load at idle it goes in to gear and dies shortly after. with the 4prong plug disconnected it still dies but doesnt sound like its under a such heaver load. did i put the wireing wrong or is the converter bad?? before the tranny went the car would die at stops sometimes just cut out at slow speeds like it wold be missing but the motor is new.

 

Not sure if it has anythig to do with your problem, but the TC lockup solenoid was different in different years - some had a normally closed switch and some had a normally open switch. Maybe your ECM is switching a different TC switch wrong? It's a longshot, I've never read anything about this when switching trans, but worth a look into - here's a tech article on how to test the switches without pulling the tranny:

https://www.thirdgen.org/forums/carb...c-control.html

Maybe switching a normally closed switch when your ECM thinks you have a normally open switch makes the TC lock at the wrong or opposite time? I dunno - like I said a longshot, but it was a thought.