Corsica overheating

My 96' corsica is periodically overheating. Replaced Thermostat, water pump, rad cap, still overheating. Lossing a little bit of fluid but not visible. Was told it was the head gaskets. Started to tear it down, but I took out the spark plugs and they don't show any water damage. I heard that GM has had some intake manifold problems. If it is the intake manifold gaskets, would it cause it to overheat? What else?

it is very possibly that you are leaking from your head gaskets or your intake...maybe even both, thats what mine did. It also could be a heater core which if thats leaking bad enough you may be able to see a green tint in your carpet on your passenger side floor board.

Have you mechanic run a scan on your computer. I have a similar problem and found that there is a hidden trouble code (wont set your dashboard warning light on) that will advise you that your electric fan may not be working (the radiator fan). The fan will only come on when temperatures get extreme.. if it doesnt work, you will notice temperature variances..especially in the summer time at idle