Noise/Vibration at low speeds 2002 Maxima

I just bought a 2002 Nissan Maxima SE with the 3.5 V6 and auto trans. Taking off at low throttle, sometimes the car get an odd vibration from the front end. It does not happen under higher accelration. It also always does the same thing slowing down. I hagve changed the brakes, wheel bearings, looked at and felt the cv's for problems(although I cannot swear they are good, but no torn boots or odd feel), changed trans fluid and filter, and done general inspection of car. This is driving me crazy! I can't figure out what it could be. Any ideas?