i am not new to diesel trucks, ive had a few and i worked at Dodge as a diesel tech, many years ago before the army. but like anything you havent done in 7 years, i have forgotten a few things so i have a question. i have a 2002 24v 6speed, 150's, 62/71/14, studs, FASS, valair single, 5", quadzilla i drive the truck with the quadzilla on level 1 95% of the time, and have been getting around 19-20mpg driving around base. im still getting the same fuel mileage, still drive the same, still running 2-cycle in my fuel. nothing has changed.i used to be able to put the quadzilla on anything higher than 3 and it would roast the tires at 35mph if you floored it, boost came on strong and violent and it was awesome. but lately it seems sluggish, boost levels are the same, egt is the same, LP fuel pressure is the same, amount of smoke is the same, no headgasket issues that i can tell, and no DTC's...nothing has changed....atleast as far as i can tell.today i was driving along and had to change lanes in a hurry, so i floored it in 4th gear with my programmer on level 2, usually this would result in me being thrown into my seat and etc....today however it made all the right noises, and all the smoke...but didnt go like i was used to. then at about 2700 rpm it felt like something "caught" and the truck went like i was used to, then upon shifting into 5th gear, the "laggyness" started again. im at a loss and kinda frustrated. any ideas whats going on?thanks for any help

Are you still able to build boost? I had an issue with my MAP senser a while ago and it was being messed up by my comp when it died. I unplugged the comp and it ran fine. Might be the tuner messing up. Just a though..

i thought of that, and it was on the list of things to try, i went out last night and adjusted and reset my APPS, that fixed it. its back to normal, and the truck runs like a champ again!

Fuel pressure? What it like between idle to WOT?Boost pressure? Error codes? Yes. Error codes can be present without a check engine light.