Ok I have been having an ongoing problem here.
I have had an 80 firebird that I rebuilt and droppped in a 350 with some speed goodies, and backed it with a TH350 with a healthy shift kit. Now I dont know the specifics here because a friend of mine who is tranny savy built it. But about a year into driving the car the tranny wouldnt shift out of first. So we tracked it down to the govener(spelling sucks i know). So after replacing the part things were good again. This has happened about 3 diffrent times in the 6 years the car has been alive. Now the same symptoms are back, but the car will not even shift with me manually shifting. I have yanked the govenor and cleaned it out. And replaced the fluid and filter. I HAVE NOT done a complete trans flush. But it remains stuck in first, or sometimes starts out in second and just hangs there, so i am forced to limp home starting out in second.

So do you guys have any ideas?
I have a stand by TH350, but it is bone stock and i am afraid this motor may tear it up. And i really dont want to yank the 350 that is currently in the car if the fix is something simple, and my lack of knowledge is holding me back.

thanks guys