Last night while I was driving the truck (V6) I had a couple of episodes where the truck started going slow. I heard a rattling sound, like marbles in a can, and a low pitched growl kind of noise. It stopped after about 10 seconds and ran and drove fine after that. Any ideas as to what was going wrong? It kinda sounded like it was to the left of the engine compartment but that might have been because I was in the driver's seat.