My 09 GMC 5.3 AFM does the exact same thing. The difference is mine is accompanied by a huge cloud of thick blue smoke. I figured it was the plugs momentarily fouling from the oil. If you try to feather the throttle to work through the stumbling it goes to 2,500 rpm and stays there, usually backfiring a couple times. GM says it's normal break in, even after giving them the "Excessive oil consumption on start up" TSB that they had never seen before.
I guess that's what happens when a gov't and union own an automaker.

 

Seemed to fix the problem guys.
Found a station with 94 octane fuel, tossed in a fuel system cleaner and conditioner and cleaned both the throttle body (which was caked with gunk) and MAFF.. seemed to even the idle

 

You need to make some phone calls and visit your dealer every other week until they do something about it IMVHO.
Glad to hear it!

 

great.. so now after cleaning my maff and throttle body my truck seems to be revving higher and holding rev when i let off the throttle. this is causing my truck to downshift very roughly. it almost clunks between downshifts. WTF is up now? the butterfly seemed to move without any sticking when i was cleaning it, and i was very very careful using seafoam and a qtip whilst cleaning the maff

 

You used a Q-tip on your MAF?!? OK, first things first. Pull your batt cables for a while and let the computer relearn. Then report back.

 

yes i used a q-tip, but i was extremely careful.. hands of a surgeon buddy.. i already did the battery pull because i was throwing a code after cleaning the maff, intake tube and throttle body.. i may do another one to see what happens..

 

What code were you getting? Where are located?

 

im not sure on the code.. i will take it in to have it scanned. Im located in Calgary Alberta and Denver Colorado