I was driving down a old bumpy road the other day and all of a sudden the truck stared shaking violently it's happpened a few times since. I checked the front end and everything appears to be tight ( Didn't find anything loose ) What could cause this. A friend of mine who is a FORD guy he had the same problem and he replaced his Trac bar and it went away. Just wanted to see what you guys think. The truck is a 94 2500 4x4