my 2001 ls1 is throwing a multiple cyl mis fire code and its back firing , could it be the coil packs ? or the plugs? i just changed the wires and didnt fix the problem , just for a fact , just had a brand new trans put in and they had to remove the coil packs on passenger side to remove header please help i dont know how to test it or what to do i just saved up allot of money for a level 3 trans and now this