my 1993 gmc K1500 460L transmission newly rebuilt will shift correctly 1st time then when you stop and take off again it seems to be stuck in high gear.
Did you get a warranty with it? I'd take it back before any damage is done.
Seems it may be the governor sticking
Search GMC Sierra 1500 Questions
GMC Sierra 1500 Experts
Related Models For Sale
Used Cars For Sale