I agree with Bob...check your alignment!!! I had the dreaded death wobble so bad that for a couple weeks I didn't want to drive on the parkway because whenever I hit a bump the "right" way the Jeep would shake so bad I would actually have to slow down to get her back under control.

I had an alignment done, changed my front shocks with the cheapest they make (Monroe gas-matics...17$ a piece, absolute garbage) and the wobble was completely gone.