Most engines should be running at 180 - 200 normally. If running to cool, your gas is not detonating as it should and you could be washing down your cylinder walls with the excess gas which can lead to early ring problems and sludge. Plus wasting gas. The gas sold today pretty poor compared to what it was 40 years ago. To get the most out of your motor, it should be running at max efficiency which usually is at 180 -195 degrees. FI engines usually 195+.

If you are getting varying results and your temp guage(s) are all correct, might want to try a differernt thermostat by a different mfgr, sometimes it could be a product error.

Of course I could be totally off base, and usually am. Which would explain the straight jacket my wife makes me wear from time to time.