I've got a Horrible rattle at 1500 rpm. The whole truck shake's, it started doing this about 2 week's ago. I first noticed it when I driving, and just thought it was the roads... It does it in neutrel too at highway speed's though. Even sitting in my drive way in park the truck shakes very badly so it's deff the engine and not trans/ or suspension. Maybe injecter's? Dampner? Where should I start looking?