Water heater issue

I am having an intermittent issue with my water heater and need advice. It's an Atwood propane only model with a 10 gallon capacity. The issue is that sometimes it will light right away like it's supposed to and run fine. Other times I have to go put there, light a stick on fire, shove it in the hole and run inside to turn the switch back on as it just won't light on its own (but the gas is definitely flowing) . Then sometimes it will fire up - nice pun huh? - for 10 seconds or so then quit and try to turn itself right back on. Usually when that happens the ignitor won't start it up and I have to do the stick trick again. Any ideas to help me track this little goblin down?