Need help!!!

I have a 2002 chevy trailblazer with the 4.2 engine.  4 months ago it started loosing power.  I took it to my frind with a code program to read codes and it came up with the throttle positioning sensor was bad.  I took it to a major chevrolet dealer for further diagnosis and the found nothing.  They proceeded to tell me that thay could put gm throttle body and injector cleaner and it would be fine.  Well that didn't work so I investigated as to where the throttle positioning sensors were located ( in the throttle body)  so I purchased a new throttle body and a new map sensor and installed both. Now when going up a mild incline it gains speed slowly, flat ground same thing. on mid range and top end its fine but if you give it gas it bogs down real bad and makes the sound of it not getting enough fuel/air mixture or too much.  It also has a new fuel pump and new fuel filter and K/N air filter.  There is no adjustment on the throttle body so I cant adjust the mix either.  Anyone have this problem or know how to fix it?  Need to get it right soon.  Thanx