Check for a leaking combustion chamber, with the Domeitic still installed.

Leaky chamber causes hard staring and flame out when driving.

Remove the chrome vent cover. Put a cork in the deepest of the two vents,
and blow into the other. It should be an obvious seal.

If not, got to find the reason, and retry. Is the drain cap off? Unsealed
box? loose orifice in box? Cracked corrigated vent pipes ( a good possibility)?

Cracked vents are caused when removing and reinastalling the Dometic.
Especially the 182b.  Very brittle pipes. When bent to much, they will crack
at a bend. If you have cracked vent pipes, remove the side grill and stick
your hand inside and feel for the crack. Never done it, but muffler cement
on the crack is the fix.