I had a similar experiance. After I was rear ended in an accident during the summer my car on occasion would have trouble idling. Eventually it got to the point where it would start, and the RPM's would immediately drop off and the engine would die. I had to keep my foot on the gas at all times when the clutch was pushed in. As it turned out the accident knocked a certain hose a little loose ( I can't remember which one) and it allowed dirt to get into the idle control motor which eventually seized up and stop working. The idle control motor is the device on the upper right side of the engine bay that connects one of the two throttle cables. A little cleaning (of the hose), and a new motor later my car was back on the road. Hope this helps...
-Matt
