After little driving my temp gauge will fluctuate from low to high to back to low then slowly creep half way up
My car has 214368 miles.
My car has an automatic transmission.
This is either caused by a defective temperature sending unit or your thermostat sticking and getting ready to go bad. Have the vehicle temperature monitored using a laser temperature tester and a scanner hooked up to monitor the temperature sender to the computer.
If the temperature rises to about 190 degrees and then goes down to about 180 and then levels off around the 190 range, then the thermostat is okay and the temperature sender reading should be monitored to see if it matches. If the thermostat goes up above about 200 or more before it opens, then it is sticking badly. Replace the thermostat if that is the case.