Have an 03 DTS. It has an engine vibration at 1300-1500 rpm. It does it in neutral or accelerating from a stop. If I'm accelerating from a stop and turning left, it vibrates pretty good from 1500-2000 rpm then goes away as the r's go up. ?????? Does this engine have a counter balancer? Could it be fuel/injector related? Dealer can't find. They replaced a tranny mount thinking it was it, and is still present.