I just fixed the furnace again!
The flame sensor in the furnace infrequently develops a very thin layer of carbon. This very thin layer of carbon causes the furnace to go out after running for about 30 seconds. at which point the thermostat say to the furnace, "hey dummy, the house is still fucking cold. turn on!". thus continues the delicate ballet of home heating. furnace on, funace off, furnace on, furnace off and so forth... therefore, i was forced to again dig inside the furnace, remove the sensor, wipe it down and replace it. certain persons concerned with this group will be happy to know I used an enjo thingy.