Have an 02 CC Frontier automatic and am experiencing something banging or knocking on the floor under my feet while driving and when at a stop while still in drive. You can feel it in the drivers seat as well. If I switch to park or N it seems to go away or not be as predominant. It does not always do this and thats what is strange. Any ideas??? Could be in the engine as well but the Rpm's dont bounce around and seems steady.