Whenever I use my power windows, my water temp gauge moves up while I hold the window button. Then when I release, it goes back to where it was before.

 

Check your grounds, your lights are putting a drain on the power, which is affecting the voltage going to the coolant sensor, consequently affecting your gauge reading.

Iceshark knows way more about this than me.
-Jon

 

Also check for crossing wires or nick wires does anything else flicker. what is ur voltage reading?

 

Replacing the negative battery cable (which looked good at first, eventually was all cracked up) with Ice Shark's replacement and problem solved (as well as a few others).