[John_AZ]

You mentioned the coolant level looked OK.

Have you noticed any small loss of coolant in the reservoir?
When you check the spark plugs, does one look like it was steam cleaned?

Before you drain the coolant and check the thermostat, "burp" the coolant system to make sure you do not have an air pocket. Lift the front up on jack stands.
Open the coolant air relief bolt, wrap a rag around the part to catch overflow and squeeze the top hose gently.

Sometimes the radiator fan switch contacts get fouled and not make contact correctly or soon enough. Replace the switch with the same temp as the old one. (3 temps available)

Make sure the contacts on the coolant temp sensor are clean.

Bad grounds can cause overheating. Clean the battery posts and the large negative cable connection on top of the bell housing. Cover the TDC hole with tape.

Clean the front of the radiator. Spray with a strong cleaner and rinse from the engine side to push the dirt out and not further in the radiator fins.

Just a few ideas.
GL
John