1994 Pontiac Sunbird my car keeps over heating

I'm afraid there is nothing you can do about the issue.

I've had the exact same problem with a 2001 Sunfire, I also thought it was the thermostat and had it replaced.

After having the problem happen repeatedly, I checked the User Manual that came with my car. I read that overheating is a natural occurrence with this car, and probably the Sunbird as well - it recommended turning the heat on full and venting as necessary. Not very reassuring I know.

Luckily, I crashed my Sunfire and got a new car. Unfortunately I decided on a 1994 Sunbird just because it fit my new snow tires that were on the Sunfire. Now I get a Check Engine light on my Sunbird with no apparent problem.

Pontiac just makes lousy vehicles which is exactly why GM is going out of business. There is only 1 way to fix this problem, and that is to buy a Japanese vehicle.

By the way, I really miss my Honda Civic. Even though it had a massive oil leak, it still ran better than the Sunfire I used to own and had nearly 500 000km's on it.

You need to replace the electric fan just behind the radiator. Easy to do. I had same problem and fixed it in 2 hrs myself.