The Exhaust Gas Recirculation Valve (EGR), is located on the front, passenger side head and has an insulated tube going to the intake manifold. If this valve malfunctions, some of the symptoms are, erratic, almost stalling idle, low speed surging, and poor performance and fuel economy. Mine went bad (with a code) at ~54K miles. When is the last time the plugs were changed? What type of plugs were installed? Has the backside of the throttle body butterfly been cleaned? Do you have a catch can? If not, IMO, it is a must on the Hemi. Take the air tube off at the throttle body and manually (with engine off) open the butterfly. Shine a light in and examine the backside of the butterfly and the intake plenum behind it. Look for caked on oil crap, and puddling in the plenum. Guaranteed you'll have it, and it will probably be real bad. This crap may affect the proper operation of the MAP Sensor, which in turn will tank the fuel economy. When's the last time the PCV Valve was changed? Once all of this is sorted out and repaired/replaced, reinstall the DS Tuner. It should work real well....it does on mine.
06 GCO, Dk Khaki, QDII, Flshing Hi 3rd Bk Lt, MDS "ON" Lt, Airtab Vortex Gens, Debadged, Fumoto Drain Valve, BT Catch Can, Chopped EGR Tube, SRT8 CAI, K&N Filter, Sonnax Trans Line Press Booster, SC Tuner W/Adv Trans Tune App, DS Tuner, Cust tubular hdrs w/3 in Magnaflow/Xlerator AP Exh Sys, Bilsteins, SRT Springs/Sways, Cust Eng Cvr, SRT8 frt/rear bumpers, FRI Sidewinder Cam/6.1 valvetrain, SLP 25% UD Pulley, BBK true 90mm T-Body, SOS Ign Coils w/.060 spark plug gaps, SRT Reps with 265/45&295/40X20's.