Wind! Wind is what caused all my grief. Furnace is working fine today. I spent the better part of yesterday nursing the furnace and trying to figure out what was wrong... and it was the friggin WIND.
I was on the phone with a factory tech. He's saying "try this.." I say "did it already". This goes on for a while until he suggests replacing the inducer assembly. I said "can't be the problem. Has to be wind related" I even did some work on the vent termination.. damn thing still wouldn't complete a cycle without tripping a 31 code. Friggin wind.