Well, it was cool enough today, so I tested out the furnace for the first time. The low fire is coming in at a temp rise of about 30.. the spec range is 25-55, so it's a little low, but within range. When it kicks to high fire, it only gets to a temp rise of about 41, with a spec range of 35-65 and then the burner kicks off without the thermostat being satisfied. There are no error codes indicating limit being open, so what else could possibly be causing the burner to shut off before thermostat satisfied? I checked the combustion and exhaust flues and they are clear.