Cooling system issues again!

Been having issues with the coolant system on my 15 JKU.

Fist time, bad radiator cap caused evaporation and loos of coolant. Last month the oil cooler went as well as the coolant tank .

Now when driving slow or idle, the temp gauge will randomly go up close to the 3/4 point from 30 sec to a minute or so and you can hear the fan ramp of really high, even with the radio on. Then it drops. Can happen once a day, few days or a couple of times a day.