I put a new air filter in the truck today. Come to find out it has an aftermarket box witch takes a big panel type filter(not sure of the name). Cranked it up and to my suprise it acted fine. It may have acted like it "wanted" to do its little reving fit that it has but never did. Could this have possibly been my problem?? Anyways, I pulled a tractor to my buddys house(first load ived pulled with it)and could definately tell a differance in the turbo sound when you let out the throttle< almost like the hopped up diesels do that chirping noise at the truck pull. I hope that this straightened it out but is that even possible??