Had it throughouly looked over by, of all places, Firestone and they've been nothing but great. They replaced the MAF sensor and the MAP sensor and it is running about 90% better right now. The driveability is improved and the stability system light (which came on the other day) is off.

A slight, intermittent hiccup remains at idle and it appears there is a vaccuum leak though they can't narrow down exactly where the leak is so they have recommended a smoke test or they have to remove the cover to the manifold to verify. That should be an issue that is under warranty so let the battle begin...as I gear up for that at least it seems to be running better so far...

BTW, they've only charged me for the diagnostic so far so I'm happy.

 

Rpms dipping when coming to a stop usually can be cured with cleaning the throttle body and maf.
It is literally a 20 minute job taking your time and quite easy to do without paying a dealer to do it. There are several write ups on the site on how to do it, I do it every other oil change keeps it idling like a champ.

 

I've done this and it was still idling rough and thowing CEL codes which is what leads me to believe its something more...

 

sounds like you have a cylinder that is misfiring, most likely the dreaded "Cylinder 5 misfire" problem caused by a leaking on one of the intake valves. To verify you will need to have a "leak down" test performed, I had this done at my local Hummer authorized service center for $120

At idle cylinder 5 was only compressing to 30%, causing cylinder 5 misfire codes and a rough idle.