Any ideas to why a pontiac sunfire would over heat?

[smacknrunketchup06]

Im looking to buy a 97 Pontiac sunfire but i want to see how much or what i am going to have to do to stop the over heating problem. I drove the car around a few blocks and it idled for a few minutes and the temp didn't get any higher. She says that it only starts to over heat on longer trips? thanks for the help!
The girl said she just replaced the thermostat.

 

[lusty dusty]

thermostat could be stuck shut those are only like 10 to 20 bucks

 

[pitbullperson204]

get a haynes manual..in my personal experience:
the fans not kicking on when it should
the thermostat in your car is the wrong temp or non existant
check engine coolant
not enough oil in car

these are only problems i have had and the fix to the overheating probs..one was a grand am, one a prix, and 1 an escort.