It might alos be that it takes some time for the poer to go from the front to the rear wheels. I have not had this problem, but others have said that it occurs in city because of allo the stop and go. the car has to keep transfrering power so it takes a liitle ttime to cathch up, also being that the car is relativley heavy and is rear wheel drive. the only other thing that I can think of is your transmission might be heating up and you might be in need of a transmission cooler.