ok my pickup has always ran bad under a load since i got it. wasnt too bad at all. it would pull it itself. well its been getting worse, the car will idle good on a cold start and now when i try to drive away in the morning it will fall on its face and run bad, buck and not pull it self. it will clear up, but still do it over a certain rpm. the problem only occurs past a certain rpm, if you keep it LOW rpms and lug it around it drives good. once it gets past a certain rpm the car acts like it doesnt have fuel or something. i checked plugs, they are good, replaced fuel filter. thought it was a clogged cat, took it off, still acted up. the cat had broken up so i thought it could have went back into the muffler and clogged it up. replaced the muffler the truck can drive well and when you part it, say you let it sit for 15 mins, it will fire up and idle fine. but if you wait say 45 mins where the engine starts cooling down. upon startup it will surge and try to die, you have to feather the gas ( pressing the gas will stall the engine, when your letting your foot off the pedal is when it revs up) also when its falling on its face. say i am giving it gas to accelerate, it will fall on its face and not pull at all, but as i let off the gas it will pick up and act fine, but only while i am lifting off the gas pedal which is less than a second lol i am guessing it may be the fuel pump, only think i can think of that would get worse and worse over a long period of time. any ideas?