I have an 04 Trailblazer (46K miles). It was great before I was t-boned in September. The body work took 2 months to complete and looks great. Unfortunately, when I picked it up, it idled rough/vibrated, especially when cold and between 6 and 700 rpm. I was hit on the passenger side and it caused enough damage that the floor boards had to be fixed along with the fender and doors. I have read thread after thread on this, and there seems to be as many fixes as there are problems. As my issue came up as a result of the accident (my opinion), does anyone have any thoughts on what might be the cause of my rough idle? The body shop checked both motor and transmission mounts. Their answer was it seems to be the exhaust. It is currently at the dealer, and they are telling me the same, but have no answer how to fix it except to add sound dampening parts. Oh, and it hasn't thrown a code.