New Cougar - Furnace wont heat above 60

Please post model number of furnace. This is important. Either furnace hitting high limit switch temp. rating, which cause an open circuit, which deletes power to circuit board, ceasing flame operation, and flame will shut off. When limit switch cools, the contacts close, causing power to re-energize the circuit board, 24 seconds later, flame will re-appear. When this sequence occurs you feel cooler air than hot , but it will not be cool air. Cause, inadequate air flow usually caused by not enough heat discharge ducts for furnace to vent heat out, or breathe. If soft ducting you should have a minimum of 4 full size tubes coming off of furnace shell and registers fully open at discharge within interior. Virtually every furnace will work better if you can install an additional discharge warm air duct.