From my experiance, if it would be a differential issue, it would pull left under 3/4 to wide open throttle. Mine did have a grinding and sluggish feeling before it went out this last time.

Check the rotors and make sure none of them are warped. Make sure none of the calipers are locked up.

Keep in mind to check and replace both sides as you see necessary. Front end noises have a tendency to "throw" the sound to the other side.