If it ran for 5 years fine...I am led to believe it is not wind related....unless you didnt have winds for 5 years.
My bet is either a heat exchanger starting to get plugged a little, a weak pressure switch, or another obstruction that is partial somewhere.
This would make the unit more "sensitive" to the wind and cause fault. I think the extention and caps are heading the wrong way. If it ran 5 years ok....I would start with clearing the exchanger, checking static pressure of exhaust fan, static of pressure switch and drain from furnace.
I would think something else is adding to the issue and the wind just puts it over the edge.
where does the furnace get its air from for the burner now?
air is from the room furnance is in. the various service and parts replaced was done. that is why it was narrowed down to the wind problem -- some say its wind not letting the exhaust vent out and the carbon monoxide sensor is shitting it down, otheres saying it is not getting enought outside air, causing it to shit down. that's why all the different solutions to solve the air problem.
Do you have a transfer grill for the combustion air?...and why was the combustion air not piped to the outside?
correct...but most 90% units have a second pipe to outside so the furnace does not use house air...thus sucking cold air in wherever it can...all the air being exhausted must come from somewhere...and without the second pipe to outside the huse becomes negative pressure.
what is make/model
I think the unit is starving for air.. The grills will surely help. But an outdoor air pipe would be the best.
if you need further help let me know.