atwood furnace not staying lit

Could be that the flame sensor (actually a flame prover) needs to be re-gapped. Atwood spec is 1/8". Over a time the gap may widen due to vibration, causing gas valve to close...

If needed I can post the full sequence but this sounds like a flame sensor issue.

Sometimes the flame sensor gets dirty and does not heat up fast enough, cleaning it makes it work better.

option 2 is burner. the orifice can be dirty and need cleaning (Reduces gas flow and thus heat) or the air/fuel mix can be off a bit.

In my case.. it was the control board, but in yours, I think not.

Clean the burner area. You may be able to just blow it out with compressed air.
Make sure the flame sensor/ignition electrode is adjusted properly.

Mine did that a few weeks ago. I switched propane bottles, got the lines cleared by lighting a burner on the stove and it has worked fine. Sounds like you may not be getting enough propane to it .