dodge ram 50 acceleration problem

i recently took over a 1989 dodge ram 50. it has the 2.0 engine and runs fine. i just had the carb rebuilt. its a nice little truck. when i was driving it home, i got to about 50 or 55 mph and it stopped accelerating. its almost like there is a governor on it or something. if anyone has any suggestions i would greatly appreciate it.

I recently bought a Mitsu Mighty Max, '88, which I understand is the same as the Ram 50. I'd owned a '77 Ply Arrow, also by Mitsu which I last drove in '83. It took me about a day to remember that it doesn't like to accelerate uphill. So on the downside of the hill, start to pick up speed, then keep the accelerator steady so you'll have enough ooomph to stay high enough in the gear without increasing acceleration and without having to downshift going up the next hill. I'd be interested in hearing other advice.