closing the loop on this. Spent a couple days with the folks at Haggai. Had me fixed up in 48 hours. Amazingly enough, the intake was clean. the VGT on the turbo was hosed and the actuator/air control valve on the firewall was bad. They think the air control valve/actuator died and then the VGT kind of welded itself shut since it wasn't being activated. New turbo, actuator, air control valve, etc., stayed at 70 whole way home, even on the climbs around Chattanooga. It might have been fixable if the shop I immediately took the truck to would have checked things over vs. just replacing the EGR valve, clearing the rest of the codes and calling it good.
I also had them run the exhaust out the side vs. just dump underneath the bed. Always heated up the ramps and I'm sure the generator breathing that exhaust was not good. Nice to hear the turbo whine now.
Burned HALF the fuel coming back vs going down.
BIG thumbs up to Haggai Automotive & Diesel in Griffin, GA. He also knows the freedomline transmissions well, has all the software, etc.