I pulled a 10.000 lb load up a long grade yesterday and all of a sudden we heard a loud scraping noise and a loss of boost and power. It wouldnt do it steady but rather jerky motion. I found if I kept the boost below 20 PSI it wouldnt occur, but if it boosted to 25 plus for 30 seconds it would happen again. The motor has a Edge chip and 4" exhaust. Is this the turbo causing this? Oh the truck is an 03 6 liter F350.