Bad t-stat, bad gauge, bad temp. sending unit, low coolant, bad radiator cap all come to mind.
Coolant condition will tell you something else too. It could be the coolant sensor is caked with sludge from a poorly maintained system. It would read a short all the time which pegs the gauge. Also could be a shorted lead in the harness or shorted board on gauge cluster
Temperature.
instrument cluster needs to come out and apart to gain access and replace gauge
Temperature Gauge Sending Unit The sending unit is located in the front section of the manifold in the vicinity of the thermostat.
195 to 210 what temperature thermostat do you have
usually on the left of the engine between the first two spark plugs
Mine runs around O & R on the gauge.
The sensor is right behind the thermostat housing.
That is the coolant sensor. Not the one for the temperature gauge in the dash.
Check the temperature sensor.
probably leaking or maybe a bad rad cap
There are two...one that sends a signal to the gauge and one that sends a signal to the computer.
Most likely cause is a failed engine thermostat.