Coleman gas furnace. Burner will re-fire for a few seconds during the cooldown. Model G8C07512MUB12A

This is a little complicated because it can be several things and you need to provide more specific info....It could be your furnace is shutting off on the High Limit...which means your furnace is running too hot...check the filter , return air vents etc would be an airflow problem...dirty blower....Furnace can be too big for your house....when the furnace shuts off on High LImit , the fan will continue to blow air , cooling it down as usual and once the furnace cools enough to reset the high limit trhe furnace will Ignite again as long as the thermostat is still calling for heat . The furnace could also be running too long and getting too hot....your Ductwork can be too small...many factors come into play