New car disaster!

I just bought a 97 Pontiac Sunfire convertible. It wasn't even what I wanted but once I put the top down I was sold. The third day that I had it it stalled out on me as I was leaving work! How embarrassing! Anyways, the problem seems to be that only when it's cold, like first thing in the morning or after work, the car will stall out and die if I don't let it warm up for like atleast 5 minutes. If I let it warm up it will run just perfect the rest of the day. I took it to the dealership to have them figure out the problem and their scanner isn't pulling up any codes and they can't duplicate the problem because it isn't cold after I drive an hour to get it there. Now I have to drive it there and drop it off so they can have it cold. I don't have any hope of them finding the problem so any suggestions will be greatly appreciated! Until then I guess it's back to driving the MX-3! It's dependable! ;)
thanks so much!
stefany