If you can borrow a ScanGaugeII or something similar from someone you can check it and make sure. It should rise to the same point every time. The only time I get it to go above the ~180s is towing up a really steep and long grade (gets to the 190s) or slow offroading.
If you want to be sure flush the coolant and replace with the Red Toyota coolant, replace the thermostat with a Toyota one, replace the radiator cap and be sure the clutch fan engages when it should.