SO I was letting my friend drive my car(with me of course) and while she was driving whenever the engine would slow down it would sound like the valves were tapping. I got the car in the driveway and let it sit a couple days and went out and started it again. It doesn't do it starting, idling, or revving up- only when it decellerating. It does it sitting still and moving. The car has oil(it does need to be changed) and hasn't been driven very much since about march. ANy guesses?