when i was driving my temperature gauge went into the red and back down to below the halfway mark and back to 3/4 to the red and just kept going back and forth. what would cause something like this.

Low coolant level.

when i was driving my temperature gauge went into the red and back down to below the halfway mark and back to 3/4 to the red and just kept going back and forth. what would cause something like this.

Or thermostat going bad..

might be a good time to change the sending unit too, they are cheap and easy.