at 98,000 miles vehicle shuttered under breaking at speeds 50mph or thereabouts. after many shops with their heads up their asses couldnt figure it out. i saw that some in here used aftermarket rotors and the prob was fixed. this is indeed the issue. chev uses lousy rotors and they warp under normal braking. do not have the rotors replaced by a shop because they will use oem rotors. this will only be a temp fix and in 10000 or less miles the prob will be back again. its brakes people. do them urself. its easy job, i just did mine at 128000 miles. prob gone.