Furnace blower door switch failing. Bypassed door switch Performed heating maintenance Cleaned flame sensor Low fire gas pressure 1.5" High fire gas pressure 3.2" Furnace tripping high limit in high fire Increased airflow to maximum It still trips the high limit Recommend low MERV rating filters, the flat panel fiberglass filters will mitigate this overheating issue Wired thermostat for two stage heating control, so hopefully it won't utilize high fire very much at all.