Bought a 91 735iL. Had trans problems. I put another transmission in it that I pulled from a wreck. However, I wasnt sure if that trans was any good. After I finished the job, the car would go only into first, and not upshift. Sometimes it would try, but slip back down to first. The question is, should I look into checking the TCM module? Is it possible that it has computer problems? Has anyone experianced similar problems?