I was backing up my car and I pushed the clutch in, the rpms started to go down but the rpms went really low to almost stalled. It doesn't do it all the time but it has done it a few times. The idle doesn't seem to be very smooth as it will drop and rise a couple hundred rpms sometimes. Does anybody have any ideas why it would be doing this? And no its not me as I was able to get to do over and over 5-6 times.