I have a 2006 5.9L and at high idle (1,000-1,500) RPM's the truck makes a woofing sound... I did a cut out test on my injectors #1 and #2 were the weakest so I pulled them and cleaned and replaced the o-rings and the little brass bushings. that made it go away for about a day and now its right back to doing it again...also which i dont know if it is related or not but I am also getting oil in my fuel filter??? any idea's? thx