[bstark]

This may sound a little technical but, Dave (rverdlm) has offered the best hope of a solution and here is how I would go about checking that overtemp out. You can isolate the point on the board that the feed from the overtemp pot comes back to the board and meter it while the furnace is running and observe if there is an interruption in current that is triggering the shutdown, if that isn't the problem go to another point such as the flame sensor to see if it is marginal and telling the furnace to shut down. You should do this with all of the furnace 'fail-safes' such as the sail switch, timer relay etc.. If you are not the least bit technically inclined, a good service guy or a friend that is handy could do this for you and it can be done during the summer when you're not as desperate for heat and can take the time to troubleshoot it correctly. Your dealers to date have simply done the basic "get-it-running,-bill-them-and-get-them-out-of-here" thingy!

berghild: These furnaces are rated at 42,000BTU's (due to the tapered duct attachment plenum on the back end) and actually do put out enough heat that you should be more than toasty in cold weather without the thing running non-stop. If there isn't enough heat coming out of the ducts I would surmise you've got a duct disconnect somewhere that is allowing all of the heat to go into the basement to be lost in the process. This can actually be worse than you imagine because the rear of the furnace is near the wall cavity (under it) that the thermostat is attched to and the heat 'escaping' from the rear of the furnace simply goes up that wall cavity and signals the rear of the thermostat that "all is warm now" so shut down.