power loss

[HummerRidin26"kmc's]

I have a 2003 h2 its been a good truck i love the hell out the thing but out of no where while i was driving one day its started feeling really slugish so i changed the plugs an wires didnt fix, so i then had tranny flushed tansfercase fluid changed an front an rear dif. fluid changed just to make sure that they werent holding it back still no luck i have a dtc code reader no codes ever showed when i crankin it an take off it will be fine an twenty mins later i feel like iam drivin a school bus flooring it every where to get around twenty mins later it might be perfectly fine again ive been dealing wit this for months now changed o2 sensors new high flow cats still nothing. also the plugs that i changed looked orangish in color. one min it feel like it has 350 hp the next min it might feel like a 150 hp this is a major loss of power randomly thank you for you time an help

[IRA51]

Find someone with a good scan tool and scan it while driveing .you may have a fuel presure problem under load. check the air filter and see if it is dirty . FYI if you have detonation the computer will keep reduceing your timeing untill the knock sensors do not detect detonation . just for fun put 2 cans of SEAFOAM in your gas tank fill with 91 octane and drive it like you stole it and see if it gets better .http://www.articlesbase.com/environment-articles/sea-foam-fuel-additive-give-your-car-engine-a-longer-life-774754.html

[H2R]

Run a fuel pressure check when its not running correct. I would venture to say a fuel pressure regulator, as a guess.

[HummerRidin26"kmc's]

thanks alot guys for your info its much needed i will keep posted on the problem any one else with thoughts keep em commin there much needed aswell thanks

[HummerRidin26"kmc's]

by the way i also have noticed i will get better gas milage if i leave the truck out of over drive as well not sure this things becomming nothing but a problem really fast i cant seem to figure it out