Highway Vibration

[abschnick]

So here is the question. When driving at highway speeds, 75-80mph, if I let off of the gas and then accelerate I get a small vibration that goes away after reaching the desired speed. I am not even doing a hard acceleration. It does not do this at slower speed accelerations, but only at highway speeds it seems. The vibration feels like you are running over real small rumble strips on the highway. Any help would be appreciated before I go to the dealer and they say, "Can't reproduce." Vehicle is a 2007 NNBS Crew Cab 2wd 5.3 AFM with 61,000.

[mattymax]

Sounds like the AFM....truck going back in V8 mode

 

Some do it, some dont