My brother and my parents Durango has this same issue where sometimes it just can't get out of its own way and other times it will snap your neck from the get go. Usually always great on the topend.

Almost seems as if its a transmission kick down issue combined with laggy throttle body. I cleaned the throttle body on both, just seems like the throttle bodies themselves might be suspect. Engines both run strong on the mid range & topend with no misfires. Its quite underwhelming going from my 04 Ram with superchips & headers to the durango, but sometimes they show flashes of greatness, just wondering why so inconsistent.