I don't know what year your dealing with, but a friend of mine had an 04 that was doing the same thing. They gave him the same answers for a while and then changed all the injectors. Truck has run fine ever since. 
__________________ HAD - 94 Chevy Dually 4x4 - 6.5 Turbo
96 Chevy Ext.cab 4x4 - 6.5 Turbo
99 GMC Dually 4x4 - 6.5 Turbo
HAVE - 2005 GMC Sierra crew/6'box - 4X4 - Duramax w/Allison. Fully loaded - AiRaid intake - 4" Pinnicle Performance Exhaust (No Converter - Straight through muffler) - EGR blocker plate - Edge Juice w/attitude - 2" plug in Turbo Resinator - |