Not sure what temp thermostat you installed, but that's the first place I'd start. Get one no higher than 180*. This will allow your coolant to circulate earlier than the stock 195* one and will help a lot.
Make sure you have that black plastic piece under the bumper...it's an air dam that forces air up into the
radiator. If it is missing or broken, replace it with one from a '93 Grand Am. It's wider and taller than our stock one and will force more air into the
radiator.
If you don't have the money for a tune (basically to turn the fan on high at 180* instead of the stock 221*) then I would suggest you mod the fan to turn on high at all times. The information on how to do that is located on
www.sccoa.com. Personally, the tune is a better way to go, but as long as you mod it properly, the mod will work fine.
Those 3 things will help your car run cooler. However, if you do have blown head gaskets (it'll cost about $30-$40 to find out for sure) I would not drive it at all. If you end up with coolant getting in the oil, it is heavier and will sink to the bottom of your oil pan. Your oil pump will then pick up only the coolant and instead of oil circulating it will be coolant. The bearings won't last more than a few minutes when this happens. Then you're looking at best, a complete rebuild.
Check your oil for any milky looking residue. That is a sure indicator that the gaskets are blown. Also keep an eye on your coolant level. Make sure it is filled to capacity when cool (before you start it in the morning). Then daily check it before you start it and make note of the level. If the coolant is getting lower then you likely have a blown HG. Also, if you have white smoke with a sweet smell, your headgaskets are blown. Those are a few ways to check. You can also go to a service shop and have them perform a chemical test on the coolant. It checks for oil in the coolant which is also an indicator that your head gaskets are blown. That test is $30-$40 depending on where you get it done.
If your headgaskets are blown there are a few things I'd recommend if you have the money. The first is to replace the stock head bolts with some ARP head studs. These will hold the heads down better than the bolts (can't re-use the old bolts anyway). You also want to get your heads re-worked at a minimum. This would involve resurfacing the mating surface, valve job and cleaning up the bowls. If you want to take it a tad further, you can get a port job done and another step further is to get larger valves installed. This all ranges from a couple hundred to around $1000. If you're interested, let me know as I've got a machinist who works wonders with these heads.
