Hi Scotty, my 1994 Ranger 4.0 V6 engine temperature gauge isn’t rising much above the cold level, no matter how long it runs. Heat works perfectly, I've flushed the cooling system, and I don't seem to have any leaks. What should I do?

put in a high temperature thermostat, if that doesn't work, replace the temp sending unit on the engine

Thanks, Scotty!

Go with a Motorcraft replacement thermostat as well for happiest result. But if the heater is adequate, it may simply have a skewed temp sending unit as Scotty said, or a bad dash gauge.