Temp gauge starts in the middle stays on H
 

I have a 2004 Ford Ranger FX4 Level II 4x4 4.0 v6 and the temp gauge is acting up. From a cold start the temp gauge starts just below halfway between cold and hot, then within a minute or so it is on H. I changed the two temp sensors and that didn't do anything. Thermostat is next but I'm almost 100% that won't do the trick. I'm thinking the gauge is set wrong. Like it's starting place is in the middle not the very bottom, although when the truck is off it drops below C like it should.

thanks for any help

the temp gauge needs reset by a ford diagnostic computer

Disconnect the 1 wire on the sender, dashboard gauge uses a 1 wire sender, not to be confused with the 2 wire "sensor" the computer uses, they look similar.

With the 1 wire disconnected turn on key, see where needle is.
Now ground that 1 wire and see where needle is.
You should get full motion of needle, all the way up and all the way down then gauge and wire are OK, if it is ever sitting in the middle then yes gauge or wire to gauge is the issue.