when accelerating I feel and hear a slight rumble from the front right, anyone experience this in the past and have suggestions?

Hello, I would consider a couple of things: Wheel bearings, and motor mounts. The case for the wheel bearing is shot down because the noise goes away, but listen for it to get worse. The motor mount would make sense in going away at speed. This is because the engine moves most as you accelerate and demand more power, and settles at highway speeds (but not completely) Since this is a quattro, the motor and transmission mounts sagging combined with the engine and transmission movements under acceleration could be causing you to hear the CV axles turning at slightly too great of an angle.