I have an 10 year old armstrong natural gas furnace which goes through the ignition cycle, everything seems fine for a few seconds, then the burners shut off. I have tried cleaning the flame sensor, didn't work. So then I replaced flame sensor- same problem. I just looked at the pressure sensor, all is good there as well. Is there a way to eliminate anything else, or am I left with the furnace control board? Fenwal triton 2461D 900-227 which is major money I am concerned.