i have recently purchased a 2001 2wd with 60000 miles. when you are traveling slow like parking lot speeds and slow to a stop you feel a thump like a bad mount or something. the dealer replaced the front calipers and rotors this week claiming one caliper was bad. i went to pick it up last night but you can still feel the problem but it has improved........any ideas? i am about to hand the truck back and cancel the deal.