We are having trouble last couple of days now that temp is near 0. The thermostat is calling for heat the furnace runs as follows. It runs on low stage for about 16 minutes and then the high stage turns on for a couple of minutes. The burner then shuts off and the blower shuts off and there is an error code 33 (limit switch). It resests in a minute or so and starts the whole thing over. Thermostat is never satisfied, set to 70, and house stays between 58 and 63 depending on night or day.
Is this furnace over heating because it is undersized for old drafty house?
Can the 2nd stage run until thermostat is satisfied or is it always going to hit the high limit under these continuous run conditions? It seems like the burner would have to run for hours straight to heat up the house enough to satisfy thermostat.

First thing I would check is the filter. Make sure it's not clogged. Is the blower coming on and is there a good amount of air coming from the vents? It would not overheat unless the filter, the "A" coil or other ductwork is clogged. This is IF the blower is operating as it should...