2003 Alero stalls

[Ron21]

I have a 2003 Alero 2.2 4 cyc. Just in the last week it has developed a problem. After the car has warmed up, when I take my foot off the gas and push in the clutch to stop at a stop sign the rpm goes down to 0 and the engine stalls. It doesn't do this all the time though and is quite annoying when it does. Also the check engine light is not on and when the car stalls only the oil and battery light come on.

I am wondering if any one knows what is causing this?