JOsh --

You cleaned the crud off the 'stat, but reinstalled it. You may have reinstalled a defective part.

The next time it overheats, turn on the heater full blast and hottest temp. The heater does a surprising job of dumping excess engine heat—and if your engine really is overheating (vs. a bad sender), then the temp gauge should return to normal.

This is a diagnostic—I'n not suggesting how you use your from now on.