2001 ranger clutch
I agree, if its over cooling, the thermostat belongs on your suspect list & a Motorcraft thermostat, or one like it with the air bleed valve & fail in the open position design is recommended. The air bleed valve will help in purging air from the cooling system after a refill & the fail in the open position will prevent over heating when the thermostat fails & that feature alone could save us BIG bucks down the road!!!!
On the misbehaving fuel level gauge, maybe try a 20 oz dose of Chevron Techron Concentrate Plus in the tank, at the pump before filling up, so you get good mixing & using Chevron, Texaco, CalTex, or now Shell, which already have some PEA in their fuel ad pack, will raise the PEA treat rate 10X above pump gas alone & may be able to clean up the sender of deposits & wake the fuel gauge sender up, so it reads normaly, IF sender deposits are the problem.
In any case the Techron $$$$ investment won't be lost if it doesn't wake the fuel gauge up, as it'll also tidy up the fuel injectors, intake valves, piston crowns & head deposits to make it run better.
Some thoughts for consideration, let us know how it goes.








