Dogde 4x4 with 5.9 and automatic..i first noticed a vibrating or a wierd noise that was on and off while driving,but would stop if i accelerated or let oo the gas pedal.now when ipit it in reverse it goes but shutters.it is also doing it in drive when i come to a stop sometimes it feels like someone rear ended me and the truck dies.it will restart easily but will shutter ubntil i take off .shifts fine otherwise what is wrong?