I had the same exact issue with my 2004 Aveo, going up and coming down the driveway...believe it or not, when it was all said and done it was a loose bolt. I had the car up on the lift when the tires weres being rotated and asked them to take a large pry bar to see if they could find it. Unfortunately I failed to ask which bolt was loose but assumed it was the sway bar.....haven't heard the clunbk since