I have a mobile home, the furnace is a coleman, the gas valve is (model 7660-326) I have let the pilot (standing) and as I turn the control knob to on, the gas ignites... I have the thermostat all the way down, I have the power to the blower off, and it still is burning... If I turn the power back on to the blower, the blower will turn on for about two minutes and then shut off, and it keeps repeating... the only way I can shut the main burner off is to turn it back to pilot... I have put a new thermocoupler and a new thermostat, same problem... could it be that the valve is stuck, or what could the problem be? Thanks