once it reaches a higher temperature the heater fan shuts off completely

More then likely this is a relay issue. What happens is the control module grounds the relay and it supplies power to the blower. If the relay is failing when it gets hot it basically disengages and the blower motor will shut off. When you shut the engine off and restart it, the relay is resetting. So we need to follow this guide on how to test the relay:

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

Once we know where we stand with the relay we can take the next step if needed. If we do then we need to track power through the blower motor circuit to find where we are loosing the power. It may be the control module not grounding the relay so we can test that when we get there.

A previous reply suggested the Blower Motor Resistor so I changed that but it did not fix the issue. With my limited experience I went to the next available part, Blower Motor. A few curses and a couple of scraped knuckles later the issue was fixed. Blowing continuously without fail. Thanks for the follow up.

I have been there many times. They are only worth it if it fixes the issue.

Thanks for the update and using 2CarPros. Please come back in the future.