I have an 05 titan and when at idle it has a very loud vibration or ratteling noise from under the hood, when the rattle gets louder the oil pressure drops, the louder it is the more it drops. When slid into neutral it goes away, apply a little gas it goes away. Its almost like a tension pulley or belt is slipping.... but I don't know and cant run to the repair shop everytime it does it. Has anyone else had this problem??