This may be a flame sensor issue.
The flame sensor rod is a small thin steel rod that is straight or L shaped. It is usually located inside the furnace cabinet near the pilot igniter or the outside corners of the burner tray.
Locate it, remove it, and clean it very good with a piece of sandpaper. Scrub is very very good, then replace it.
Let me know if this does the trick.
Could this cause an intermittent problem? sometimes the furnace will keep lit.,other times it still lights ok but goes out after 4-6 sec
Yes it definitely can cause a intermittent problem.
thanks, XXXXX XXXXX that
Corrosion can build up on the flame sensor rod and prevent it from sensing the flame consistently.