I shredded 4 serpentine belts, and had the AC condensor bolts back out, an a couple other ones as well. It was because the mitsubishi mechanic put my balance shaft 180 out of phase. It was still lined up on the marks, but 180 out. My seat vibrated at about 4K as well.

Here you go: https://www.evolutionm.net/forums/ev...-belt-4-a.html