Hi, I have a 2005 Titan Quad cab and since it's cold in NE Ohio, I have noticed that I can only get heat when I am moving but when I stop (lights, parking lots, etc,) it only throws cold air. My temp guage moves to where it always did. My truck also is leaking a few drops of antifreeze up front over the past month or so. Does this sound like a stuck/worn out thermostat? What would be an approximate cost for repairs?