Normal Operating Temperature?

Thanks for all the advice, everyone! I've verified the coolant level is correct. The lastest issue is that the temp gauge now drops to full-cold once in awhile, so I suspect a flakey connection somewhere in the harness. I'll try connecting a resistor to ground at the sensor end of the harness, and start jiggling things to see if I can track down the bad connection. Anyone know if there are some typical failure points in this circuit?