My 99 Dakota 318 doesn't heat up like it did during warmer weather. The gauge stays on the lower end of the operating range. That in and of itself isn't really the problem, it's that the best the heater does now is cool air, not warm or hot. I'm thinking thermostat, but before I tear into it in 10 degree weather, I thought I'd see if anyone has any other ideas first. Oh yeah, it's 4WD, with 160,000 on it and no fan shroud if it matters.