Well, I washed my car today real nice and purty and when i got in and started it up, i was just about to pull out when the engine dropped down to about 550 rpm and started chugging...i reved it a little bit and it went away. Later i went to AutoZone just to screw around and got in and it started up fine. Right after that i went to get some pizza and i got in after that and it dropped down to about 480 rpm and was chugging again. Ideas? Thanks.