If the truck it totally stock, and no mods have been done to it, then it sounds like the EGR valve or the EGR cooler is plugged. To clean the valve, take the intake tube and the EGR valve off and clean the heck out of the valve. If the valve is not too bad, then the EGR cooler is plugged. Take the EGR cooler off and soak it in a 100% solution of Simple Green for 24 hours. That should take care of it. If you were a northern truck, I would almost guarantee this is your problem. Being a southern truck, you will have to dig around. If you spend a lot of time idling, then this is likely your problem. I would also look around for another opinion and try to find a dealer that has a real diesel tech working there.
2006 2500HD LBZ 4X4 CC/SB LT3, 265/75R16, Rhino Liner, PCV Reroute, Resonator Plugged, 35w 6K HID Low Beam & Fog Lights, LED Interior Lights, ISSPro Pyro, Boost, & Rail Pressure Gauges in A-Pillar, Cognito Idler/Pitman supports, more to come soon.
1996 K2500 Suburban 7.4L, 265/75R16, Brush Guard, Nerf Bars
Last edited by lugnut; 12-05-2011 at 08:00 PM.