help!
 

I have a 1993 blazer , with a 5.7 tbi, has shorty headers, edlebrock intake, small towing cam, msd street fighter box, and 8.8 mm wires.

Problem is at WOT it dies down nasty, at bout 3k rpm or 4-5 just depends. It will pull then fall flat on its face and stutter and what not. at partial throttle it pulls way more how it should. I have replaced just about everyhting, entire distributor, cap, rotor, plugs, wires, tbi, fuel pump, fuel filter, and it still does it. only thing i have yet to replace is the 02 censor. any help would be greatly appreciated. this is espeacially a problem when i go mudding or to do some surf fishing in the sand it starts boggin down on me and afraid it wont have teh power to get me out becasue of this issue. power is there, just like i said stumbles horrendously at wot at about 3-5k and i will not surpass that rpm, even sounds like it backfires thru the tbi