95 Grand Am Overheating

I have a 95 Grand Am SE with a 3.1L Engine (6cylinder) that keeps overheating. Checked the fan. Sensor had previously gone out on fan, so it's rigged to stay on all the time. Still runs. Changed the thermostat. Changed the water pump (which looked like it needed to be done anyway - looked horrible and half ground up!). Finally took the thermostat OUT. Still overheating (primarily when in IDLE, but still overheats while driving). Oil looks fine. From what I'm reading, it's probably the heater core. Any good way to check, and if not, what else could it be?
Thanks!
Amanda in Louisiana

Btw, if the heater core is clogged, can it be fixed or does it have to be pulled or replaced? Thanks!

I have had a simalar problem. You woul probably see some signs if the core is bad. Look for coolant below the AC lines on the firewall. Maybe fogging of your windows. I would guess you have a similar problem to me. Have you got the air out of the system. These cars are monsters to bleed. Pull it up on an incline and leave the cap off while the engine is running. You will hear and see the water burp out. This takes about an hour. I have been running mine for about a week and ahalf with no problem until tonite. I think I hit another air pocket. Try this it has worked well for me.

Sorry, I'm ignorant and doing research to point others in the right direction to do the repairs. I'm just computer smart. Where are the ac lines on the firewall?
Thanks!

First of all, your not ignorant. None of us knew any of this at some time or the other. If you look on the passengers side of the firewall, you will see 2 silver/ aluminum lines going thru the firewall. Below the one that is closest to the center of the vehicle is a rubber hose. You will probably have to feel under the AC line to find it (don't do this while the engine is hot). If the bottom of the line is kinda wet and sticky, your problem is most likly the heater core. You can get one for about 30 bucks for an aftermarket brand, and about 80 bucks for an original equipment. Depends on how long you plan on keeping your car as to which one you buy. The big headache is replacing it. Good Luck, and let us know how it goes