2002 lesabre custom vibration

i have a 2002 buick lesabre custom with a wierd vibrating issue.driving straight on a smooth road you dont feel anything but driving on roads with dips in them you can feel a vibration when the car suspends down.you can also feel the vibration when you turn to the right,does not do it to the left.also only vibrates when in the accellerator.
i have replaced both hub/bearing assemblys and replaced tires.please help!

Almost impossibe to diagnose over the net, loose/broken motor mounts, bad ft axle inner cv can match your symptoms.

This does sound like a tough one but I would thouroughly inspect the CV joints.