I replace my old furnace last June with a new (goodman) furnace in the summer ,now I am havig b=ng truble the pilot goe on the furnace runs for about 4 second then shuts down then the pilot lite lites the furnace again it run for about 4 or 5 secons then shuts done again this goes on for about 17 times in a minute qany help thank nyou

Clean flame sensor.