1999 Voyager steering wheel shakes ?????? sometimes ??????

1999 voyager 161,000 km steering wheel shakes at speeds over 60 kmh but only sometimes ? We also feel and hear a clunking sound coming from the front end . Below 60 the clunk will go away and steering wheel is normal. Lastnight we took it and there was no prob on the way where we were going but on the way back there was a clear difference in the drive. Shook Violently. This morning I took it out and we hit 80 kmh and there was nothing wrong ???????
Please Help !!!!!!!!!!!!!:banghead:

Recommend you rotate the tires front to rear first for the shake. Your clunking may be an inboard CV joint if you hear it while accelerating or decelerating.

Thanks I was thinking the cv joints as well , along with the ball joints ....maybe. I just dont understand why it happens one time then not the other ?