When letting off the accelerator, a pulsing (not jerking) of the car occurs. It happens once the engine is at a steady RPM usually when going down a slight incline. At first I though it was unevenness in the road or street but don't think it is such. The tachometer also bobs when this is noticed. Will occur with or without cruise control on. Otherwise the engine runs great. I have replaced the throttle control sensor as well as the mass air flow sensor. Neither seem to have helped. The car has 19,000 miles. No warning lights on. Has been doing this for several months. Any suggestions appreciated.