Maybe the sensor right next to your thermostat has a loose connection or went bad. Never had this happen but that's what I'd check first.
2002 3.0 v6 2wd White with blue stripe
New tranny, heads, valves, wire harness, instrument cluster, CPS + sensor, free!brake pads, alternators, and starters for life! New MAF, radiator, hoses, coil pack and too much to list everything
Drive it hard, break it, and when you get to fix it you can trust it better.