Sure you got the right thermostat. Mine stays at 180 all day long never over.
Also when it cools off pull the cap and fire it up, see what it does, do you notice movement in the fluid(only Movement after the Thermostat opens). Do you notice Bubbles. At round 180-190 did you see the motion of the fluid pick up.
Just checked you could get a 195,180 or a 160 thermostat. I use the 180 cause here in the winter 180 works the best.