I have changed the flame sensor and cleaned the pilot light. It still has problems lighting. Pilot comes on but the burners don't light all the time.and when they do I can here it go woooosh! Like its getting gas but the pilot isn't lighting it right away. Also the furnace is propane not natural gas. When the module that sends the message to the gas valve to light. It makes a clicking sounds when the fas turns on. It should click once and the furnace should light. And some times it does and other times it will click and the furnace will light for a few seconds. Then go out then click again. And stay lit for a few seconds. And the process starts all over again