I had a similar problem with an inboard joint of mine. Turns out the "remanufactured" driveshaft I replaced my stock axle with had a bad inboard joint. It wasn't as bad as what you are describing but it sounds like the same problem. The easiest way to fix that would be to get a new driveshaft. You can rebuild the joint and re-boot it but it is hardly worth the effort considering axles go for like $60.