my 05 f 350, if im running 65 or 70 and hit a bad bump the entire truck starts shaking, and feels like im bouncing a tire down the road like a basket ball. it wont stop untill i slow down to about 45.
i have replaced all 4 shocks and all 4 ball joints, that helped a bit for a while but didnt cure the problem and lately it has gotten worse than before. any idea what would cause this?

 

check drive shaft u-joints and wheel drive shaft joints if u have 4x4.