2004 Camry vibration when decellerating

I've got a problem I hope you guys can give me some advice on. In the last week or so I have noticed that my 2004 Camry (4cyl automatic...base model) has begun to have a vibration when you let off the throttle. The vibration is coming from the front of the car and seems to be the right front specifically. It also seems to be most noticeable at highway speeds. I have ruled out a tire balance problem since it only seems to happen when I'm off the throttle and since I rotated the tires and the vibration did not move. I have also ruled out a warped rotor since it only happens when I am not using the brakes. The car has approximately 150,000 miles about 90% of which was interstate driving. I'm guessing it may be a CV joint going bad but I took a look at them and they seem ok. Any ideas what might be causing this?