i have checked all the electrical side and it checks out fine. new solenoid just to be safe. the transmission shifts hard 1-3 then just kinda goes blah. noticed i really gotta give it some fuel to get it to go up the slightest incline. downhill is fine. car has alot of power on flat and downhill roads. im ready to just put my old transmission back in. that one behaved nicely and never slipped.

history;
just swapped from tbi to tpi, used whole drivetrain.
fluid was clean when installed but a week later already dark and ummmm yea changed filter and solenoid at this point and a week later same thing.
if i stay at a steady 2,000 rpm i can drive from 45-80mph. meaning if i just hold it, not getting into it or letting off. a slight hill and itll go to 45 real fast unless i get on it. no strange noises but i am noticing that the 2-3 shift is beginning to get longer. bad transmission?

 

this is my 6th third gen, im not a newbie to f bodies. just hoping i overlooked something that a trans guru may point out. if not i am swapping for my old one.