I have a 2016 2.7 eco boost F150 the temperature gauge fluxes all the way to H. I’ve already had the cylinder head temperature sensor replaced twice, the water pump and the thermostat.

 

I had water pump, thermostat done in mine, and it acted crazy, getting hot, fluctuating, fans running full tilt.

Replaced napa thermostat with ford one and it was perfect after.

Mine is a 5.0. Ignore me if it did it pre-thermostat change.

 

Replace the thermostat with an OEM one. It's 10.00 and just might fix it.

 

Lots of reports of after market thermostats causing higher temps in these trucks for some reason. General consensus is to use only the Ford OEM thermostat.

 

The cooling system in the 5L is different from the norm. Its called a Crossflow.
The coolant enters the water pump from the bottom of the radiator and Thermostat and splits between the banks; a different path than the old type systems.
The Thermostat controls flow at the beginning not in the return out of the engine.
The Thermostat is a special 'tranfer type' that changes the flow path with temperature as needed.
Thermostat is already on a second design improvement.
After market Thermostats may not work as the factory design does, and cause overheating.
When this system gets upset with the wrong Thermostat, the Fans get involved when they should not.
Take a look at diyford.com ford coyote cooling system performance for the whole design description..
Good luck.