Our luxaire is a high efficiency model and frequently will shot off before the requested temperature is reached. We just had the "Initiator Motor" (power vent motor) replaced because it seized up. I thought the issue was related but it is not. The problem happens several times/day. If I shut the heat mode off on thermostat and then turn on in a few seconds, the furnace comes back on and sometimes will reach the set temp on the thermostat. When the motor was replaced the technician cleaned the flame sensor tip. Any ideas?