Temp Gauge went to high

Maybe it is running higher than it should. Best guess would be to change the temperature switch for the engine controls and possibly the thermostat. Your engine has a "cold start sequence" and it will increase RPM and enrich the fuel to allow the engine to run better when cold starting.

The problem is the loss of signal after the engine warms up. If the water temp gauge seems normal, likely the temperature sensor is causing your problem. There can be 2 temperature sensors on your truck, one works the dash gauge and the other works the engine controls.

Replace the temperature gauge sensor with a new one. It should work. Just to confirm if it is faulty, remove it from the car but have it connected to the car temp meter to monitor the reading. Put your sensor in a pot with water over a fire and boil it. If the temp rises steadily, sensor is okay. If it doesn't, then replace it. Good luck.

check the circuit to the tem p sender unit by removing the wire at the sender and turning on the ignition touch the wire to the head . The gauge should got o hot. This indicates that the wire is ok . Remove and replace the sender unit as it is shorting out inside and is not showing a resistance. The higher resistance __cold water --the lower the gauge reading. The lower resistance the more current allowed through so the gauge goes up

Sounds like your coolant level might be low. At highway speed you probably have enough coolant and with the air passing thru the radiator keeps the temp down, but at idle not so much. Or depending whether you have a belt drive or electric fan. Belt driven, could need a new belt.

the way to check the thermostat is with the motor hot feel the upper radiator hose to see if can squeeze it. you should be able to squeeze it. the water pumps is big problem to

Given the outside temperature, that is what I would expect to see. The coolant temp is only increasing in fast freeway driving because the engine RPM is constantly faster than around town operations.

Not sure why you would be worried.

Is the radiator fan still coming on ? Is the compressor running ?

I've seen it happen many times on the older Caravans, if you hit a really deep puddle, the splash can knock the accessory drive belt off of its pulleys. You can just gently pry the belt back on, consult a service manual for detailed installation directions.

sounds like the thermostat has gone,you stop and the fan starts to keep the temp down to normal.

jtg