A clunking noise COULD be the beginnings of bad universal joints on your drive shaft. You should not only hear this clunk when you come off the accelerator, but also when you put it into gear from park (Drive or Reverse). Thats the best guess I could give you. Tou should have two universal joints (also called U-joints), one on each end of the driveshaft, change them both.
I hope this works out for you
Saturday, December 1st, 2007 AT 11:07 AM