Overheating peoblems in 1997 Pontiac Sunfire?

[Economist]

I have a 1997 Pontiac Sunfire and have recently had some overheating problems. Once I had to stop and when I opened the hood, the coolant was leaking out of the cap. I thought that was weird because the cap was closed tight. The car is fine in the first 20 miles or so and then the problem starts. I had had the cooling system flushed about 6 months ago. I am wondering what the problem could be. Is there anyway I can figure out the problem? I am a college student and very tight on budget. Any help is greatly appreciated.
Thanks.

 

[mike]

possibly it is the thermostat. but if it was leaking out the cap, maybe somewhere in the hose or radiator there is something stuck so some of the coolant is getting backed up.

 

[freakeydink]

first thing I would do is check\replace the thermostat most of the time they stick shut and can not let the fluid circulate.