check your body mount under the cab on the drivers side floor (under your left foot)it may have broke or settled down one sign of this is the uneven gap between the fender & the door i've seen a number of the older blazers rot and the cab settle so far they even loose reverse.here in nova scotia ca they use salt on the roads in winter and its not uncommon for a 3 or 4 year old car to have rust holes. good luck jj.