I've noticed a similar issue with my 06 V8 2wd. When at stop lights,I'll turn off thenAC,shut the truck off,then turn it back on with the AC still off. Once I start moving,the acceleration is improved and I'll turn the AC back on. I've also noticed when it seems to lag and I think what happens is it shifts a tad early,if I play with the throttle,I can get it to accelerate the way I want it to and shift at a better time. It's kinda hard to explain, but basically when it lags on acceleration,I'll let it down shift a gear,play with the throttle a little until it improves to where it starts acting right. Definitely something I've noticed happens more often when it's hotter