Was the heater an issue prior to the overheating? If not, it sounds like there could be air in the cooling system.
Also, is there any damage to the front of the vehicle that could prevent proper airflow? Do the cooling fans turn on when the engine is too hot? By any chance, was a traditional green coolant mixed with the original Dex-cool coolant?
Do me a favor. I attached diagnostics below. They explain how to diagnose an overheating issue. Many of the things listed, you have done. However, there are others that may be helpful. Take a look through them and let me know if they help.
Also, pic 3 provides the coolant filling procedure. The last pic shows the air deflector under the front of the vehicle. Make sure it is attached and not damaged.
Let me know what you find.
See pics below.
Images (Click to make bigger)
Wednesday, March 23rd, 2022 AT 5:41 PM