car stalls at stoplight

1995 Sunfire - after driving on the highway at speeds over 60 MPH for longer than 10 mins the car stalls when stopping. The oil light and battery light both come on. Put the car in park and it starts again, but if try to shift to Drive or Reverse then it stalls again. I have to keep it in neutral and with my foot on the gas and throw it into Drive to get going again. Had the oil changed and the problem went away for about a month, now it is happening again. If you let the car sit for an hour after stalling and then start it, it works fine. I can drive it at speeds under 60 mph for a long time and it doesn't stall. Anybody have any ideas?
It does have a head gasket leak that I have had fixed by pontiac 3 times. They will not fix it again because the car has 120,000 miles. I need this car to run for another month or two.

I have heard of the tourqe converter in the transmission not releasing when it's supposed to. This will cause the car to stall when you come to a light and why it restarts when you put it in park. Could also be one of the sensors on the throttle body like the IAC motor.

My 95 did the same thing. It is your TCC Cilinoid inside your transmission. It'll cost you around 800 minimum. A cheap part but labor is lengthy. If you need a quick fix (although it does have its cons) you can always unplug your overdrive. That is what I did 2 years ago, and mine is still running.

Had this exact same problem on my '95 Sunfire. Turned out to be the torque converter clutch solenoid. Got it fixed for around $250 at a transmission shop. If you're mechanically inclined you might want to check out this page: http://autorepair.about.com/cs/doityourself/a/aa100302a_3.htm

Good luck! I know how frustrating it can be for your car to stall, especially at stop lights/signs!