It was great to come across this Web Site as I to was experiencing the identical symptoms that Pete describe. I could not have written it better myself and it has been extremely frustrating and annoying particularily at night trying to sleep and feeling helpless as it went through this cycle.
Thanks to the great responses, I cleaned the flame sensor as it had a slight corrosive build up as well as checked the pressure switch continuity by blowing into the diaphram while measurinbg across the switch.
So far it seems to be working. The diagnostic light description is confusing as I to had 6 flashes that I interpreted as "no call for heat" leading me to beleive it might be related to the thermostat as well. Thanks to all!!!