Sorta of the same scenario I have. We have had some cold weather here in FL the past few days, and with the heater on, the car will not reach operating temp. when moving along. The heater itself is removing the heat from the water, and the cold air flowing thru the core is enough to cool the water to the point it does not get up to temp to open the thermostat, henc the gauge needle stays at about 170 degrees, now if I stop in traffic a wwhile, or go though a drive though, it will start to warm up, but once the car is set in motion, the temp drops right back down real low.
The heater alone is doing all the work at removing the heat from the water flowing in the engine.
My moms 97 EXPLORER is the same way but more so. She complained the temp gauge wwas not working. Well after an hour of running in cold weather, I can still put my hands on the engine and it is just nice and warm. It took some driving off road to get it to warm up, but as soon as your easy on it, again, the cabin heater pulls the heat out of the water and the temp. gauge goes back down.
DARN THESE EFFIECIENT RADIATORS!!!!
