new 4.3L 6cyl in 1995 chevy g20 no power

more detail on the "struggle" - i turn the key and it starts good, idles good, then seems to have way less power at the lower rpms, once it gets to 10mph(in 1st gear) it goes a little better...then shifts, and that is when it feels way weak. if im going uphill at all, or the a/c is on, it wont go any faster. if its on flat ground or downhill, it speeds up really slow(got lots of one finger waves lately in traffic). if i get to 50 mph, it can hold it...until i hit a hill, then slows down(sounds like bogging out) while im still on the gas, until i get to 15 mph, then climb the rest of the hill in 1st gear. feels like im dragging a house, but much more noticable at lower rpms. doesnt misfire, and triple checked timing. the old motor was in bad shape, but didnt have this problem at all

anybody?

awesome - got it fixed, couldnt have done it without you - wooohooo!

Hey there! My name is Kyle and I have 95 chevy G20 and I have exactly the same problem as you and I thought it was the transmission fluid but really doesn't seem so! I don't know a lot about cars so I am wondering what your problem was and how you sorted it out? Thanks so much, hope to hear back from you cheers Kyle

it ended up being the distributor - after the new motor was in, we checked everything about 5 times...then i took it to get a electrical diagnostic, and found that spark was all over the place - there was alot of play in the distributor itself(not just the cap and rotor). switched it out, and it started running like a new motor should...and still is now. my old motor was pretty beat, it wasnt too great at hills to begin with - but now its like the hill isnt there. i noticed the idle was way smoother also, so the rough idle was why we kept checking timing

Wow okay awesome that is super super helpful:) thank you very much for the reply I really appreciate it!!! when we go over 55 it begging to shudder like it wants to change gears and on the hills it's super un powerful is this similar to yours??? And do you remember how much it cost to repair the distributor? Currently stuck in eureka and wondering if we drive it down to San Fran if it would be a bad idea? Thanks again I really appreciate it:):)

no problem - the hills were the worst, but a couple things would narrow it down...did the problem start gradually, or suddenly? does it idle good, and drive good in low/high rpm, or just happens at high speed? any rough shifting between gears? i would definitely check the spark plugs, wires, and distributor cap before replacing the whole distributor, they are way more common to go bad and has similar effect. i was thinking it could be the transmission at the time, but it was acting funny because of the serious lack of power. i took it to a shop for electrical diagnostic($100), and wished i did it right away - well worth it - it tells you if all the cylinders are firing properly, or which one(s) arent.