Factory code download

[Screeper]

I thought some might find it interesting that I was having some problems with my 2004 that included a mild bogging of the engine below 2000 RPM and extreme downshifting (up to 5000 rpm) of the transmission when on a very slight incline on cruise control. I had read on the forum that the cruise control problem was common so it was with not much faith that I went into the Coral Hummer dealership for a fix. I was told that the factory had come up with some new code that might help but not cure the problem. When I got back my truck I could immediately tell a difference. No downshift on slight inclines and only a smooth downshift on steep inclines as you would expect. Here is the kicker. My Highway mileage before the fix was a lucky 11.5, after the fix, 13.8 with more acceleration across the board. The only thing I can figure is the truck must have been running very rich from purchase. The new codes leaned it way out. Has anyone else had this fix done??