running noise

I have a 1990 trooper 5 speed manual 4x4 -- has come up with a noise. When driving and hit a pot hole on the right side a rubbing sound will happen for a couple of seconds and then go away. It is done with speed, I heard the noise and put in the clutch and coasted to the side of the road going about 25 mph. The sound would slow down as the car slow down like it was something rubbing against the tire. But much louder... I thought it was front wheel bearings. Changed them and still the same..Any one have that problem??? Could it be the center bearing for the drive shaft??? I tow it behind a Motorhome.... HELP