I have a similar issue on my 08 4.7L Dakota. When I go up a hill or even on flat road it seems like it has shifting problem and doesn't have the power or torque it should have. Unfortunately I have not gotten anywhere with that problem. I have been to three dealers and two tranny shops and they feel what I am feeling but they can't figure out what's going on with my truck. I did all the same things your talking about, I replaced throttle position sensors, throttle body, pedel sensors, you name it I replaced it. So unfortunately I have been driving with that problem for over two years hoping one day it will either throw a code, or break. I'm almost at the point of just replacing the whole truck, hey new Ram Rebel look nice! If you get your truck fix post back and let me know I'm curious to see what's the problem and what else I can try before I give up on mine.