I recently found out that propane appliances sometimes just need good old cleaning. I had a fridge that had a similar problem in that it wouldn't stay lit. With advice from others on this site I performed the simplest task first.....removed the burner & orfice and soaked them in alcohol. Then I cleaned the rest of the general area with compressed air including blowing out the flue. I put it back together & it runs like a charm.....total cost $3.50 for the denatured alcohol plus less than an hour of my time!
Try cleaning it & good luck!!
2004 Chevy Silverado 2500HD - Duramax/Allison
2009 Komfort Trialblazer 285S