Good to hear you’ve fixed the problem. But sometimes the fans can also cause such a problem. I had mine fail a while back. It would work at low speed, but when it was supposed to run at high speed, it wouldn’t run.
Came to the conclusion that it has a high and low speed winding. Has two power wires, one ground wire. After replacing it the car hasn’t had any overheating issues. I used an AC Delco fan assembly. Happened to be made with a Bosch motor. It’s a little louder than the old one at high speed, but really keeps the coolant regulated much better, especially in the hot Texas summers.
I also did replace the thermostat before that thinking it may be an issue. But it wasn’t really. But the old t-stat was in bad shape where it has a rubber seal in the center. Probably had been bypassing coolant. I noticed the car warms up quicker which is much better. Especially in the winter when you want the heater to get hot quickly when started from a cold start. Also make sure not to use a cheap t-stat. They can cause issues.