I have a 1990 yj . 4.2 engine. Yesterday the guy who does the work on the jeep put in a new HEI dizzy and a new 2100 carb . The cat was taken off and hi-flow muffler put on before the carb and dizzy. The problem I was having before was that going down the road in 5th gear it would start to slow down. When I come to a small hill I would have to down shift into 4th or on a good hill 3rd. . The jeep will not go over 55 mph . The jeep is set up with a 6 inch lift and 33 tires. I bought this setup this way it looks cool it doesn't ride to bad but has no power. The engine doesn't smoke or use oil, ( leaks some) . But putting this new dizzy and carb on wouldn't you think it would wake it up a lot. He said that he took it for a test drive and said you still have to down shift on hills. What do you guys think the problem is and what can be done to fix it. The guy working on it thinks the dizzy is bad and I'm sending it back for a new one. Do you think the big tire and the gear is the problem or something else.