I have a brand new 2014 Ram 1500 big horn 4x4 V6. As I come to a stop, the truck makes a thump thump or clunk clunk noise from the back or the middle of the truck. And the truck shakes with the sound. It's almost as if when the truck downshifts to 1st gear at the stop, it thumps after it gets into gear. It happens about every few stops at a red light or stop sign. After that it is fine. It shift into gears perfectly as I accelerate. Only when I stop does it present a problem.