Sunfire 97 - stalling problem. Help!

Hi there,
I started to have this problem a few months ago and it seems like it's getting worse...when I start the car it starts fine but if I don't start actively driving right away it stalls...like I'm waiting for the gate to open - it stalls...waiting for the traffic - it stalls...but when I drive it for half an hour or so it gets better...it doesn't stall as much...
Does anybody know what could it be...idle sensor maybe...fuel pump...???

Well, I had this same problem, but It was on my grandpa's 91 lumina. We figured it to be the throttle body had built up some gunk right around the idoler position, and with a few cans of throttle body cleaner, the problem was all but a thing of the past.