For the last two years, I've had this issue where I'll start my truck (usually in colder weather), and the temperature gauge (lower left hand on the left side of the tachometer) will remain "off" and there will be a "check gauge" warning message on the console. Turning the truck off and back on again will cause both the indicator to work and the "check gauge" light to go off. The gauge will also respond very slowly when it does work.

I have replaced the engine temperature sensor at least twice. While this works for a while, the problem reappears within a few months or the first case of bad weather.

What should I check/replace next before I take it to the dealership to see what's wrong with it?

 

The gauge is driven off of the PCM. It's a digital signal on the PCI bus.
You might want to check the connections there,

It could also be a bad (cold) solder joint in the cluster.