Hesitate when letting up

[dmcdlrn]

I have a 97 Jimmy 4x that I only drive in the winter. I have been running it for a few weeks now and this year it seems to have developed a weird hesitation problem. It seems to occur around 60 mph and higher, more prominent at 65 to 70. The weird part is that it seems to only happen when you let off the gas some. If you are under accelleration or some form of under load such as hill or wind it doesn't do it, but as soon as you let off the gas some it starts hesitating. (let off some, not completely)

I'm wondering if it is a sensor or something. No check engine light going on and I had them scan it anyway. I question the TPS. The fuel filter was changed last year and the transmission was rebuilt as well. I put the truck in 3rd to dissengage the lockup clutch and it still does it so I doubt it is the tranny.

Any ideas?