Won't pick up Speed on 1990 Isuzu Trooper

It's actually an 89'. When I get close to 25 rpm my car starts jerking, and then I switch gears, and push the gas pedal down to the floor and it feels like I'm riding the break! it won't go faster. What's the problem? what do I need fixed?

4 answers
Try a seafoam treatment, it really does wonders,
But it could be your torque converter in your transmission, or failure to get enough fuel to the engine.
I would check for a restriction in your exhaust system, like a plugged Catalytic Converter.
Fuel filter if you are lucky or fuel sock in the tank if you are not
it is the cataylic conveter stoped up im having the same problems with my 1995 ford escort 99.9% sure