Hey, I recently bought a 1990 Isuzu Trooper man trans. 2.6 L engine with 120K on it. I have had a weird mix of problems with it and will try to explain them all in case you guys think they may be related. My biggest complaint is that the truck has poor acceleration, especially when going up hill. Thats somewhat of a problem since I live in the mountains. If I drive up the canyon roads.6% grade.I have to take almost the whole thing in 2nd gear at 25 mph or so while the tach reads 5000rpms. If I try to shift up the engine can't maintain speed. It's slow off the line too, and doesn't seem to give me much power untill I get to about 4000rpms. In addition, the engine has a tendency to hesitate. Rarely, when starting off in 1st the engine will start to rev up and then chutter and loose all power. The engine stays on when this happens, but I have no power and have to put the clutch back in and try it again. Sometimes it will start normally and sometimes I just have to ride out the loss in power untill the rpms creap up and it starts to act like normal. I know the throttle body was rebulit about 1 year ago and the guys I bought it from only drove it 100 miles in the last year. I also know the fuel pump was replaced about 2 years ago. The plugs were replaced 1 year ago, slong with a leak in a head gasket and a new air filter. The truck seemed to improve in the hesitating when I put some fresh gas in it. But its still got the poor acceleration. Any ideas?