Wings, Dodge has had the "death wobble" problem for many years, some so severe they actually recalled thousands and thousands of entire trucks in a buy-back deal. Newer trucks seem to have seen the problem subside. Read a little info here:
http://leftcoastdiesel.com/wordpress/?p=206
Also a search on this site (Keystone forums) will yield similar conversation from a couple years ago. Good luck to you.