This is my first post here, I have been racking my brain for about a week trying to get a customers C5500 rollback going. I have rebuilt the fuel filter head to no avail. Other issue I'm having is no top end power. Wont even pull itself at the speed limit in a 5 mph head wind. Zero codes, makes desired rail pressure and right at 17 psi of boost. This is a new long block, swapped injectors and all other parts from old engine(had 4 scored holes)