I have a 1991 lifted chevy truck and the original fuel tank will not fit…
I had the starter, alternator, battery and wires to all those components replaced. Sadly when I picked it up, it started up that was great. The sad part is first the odometer didn’t work. I know how to reset that. But the worrying problem is when I drove it, it didn’t want to go into second gear. Its like the rpms just went up. You could hear the engine scream driving at low speeds. Usually that would be cool but this is my classic so its not cool at all . I think it may be a speed sensor or the transmission is toast. I don’t understand why it would go if it worked fine before hand. A rough idea of what it was like, imagine driving 10 miles an hour which I was the whole way home and then the engine was roaring rpming like it was at a drag strip going 80-90 which is this vehicles top out speed because its stock.
Generally being low on transmission fluid will cause what you are describing. The transmission is slipping. If driven to hard or to long like this permanent damage may occur. If you where displeased with the performance you probably should have driven right back to the shop. I would have to guess it didn’t run at all when it was taken into the shop so they wouldn’t have any idea that it wasn’t like this when it was brought to them. But I am sure they would have been more than happy to check your transmission fluid for you.