Did you install the rubber O ring that attaches to the thermostat that makes the seal between the thermostst and the housing? If not coolant will just flow around the thermostat and you will never get correct operation. I almost forgot mine when I changed to a 180. This is the first car I ever saw that had a setup like that.
Is the 92 supposed to have the same rubber O-ring? All I remember when replacing my stat was the standard issue thermostat gasket, which goes on the outlet side of the housing, not the engine side.