You may have a blocked orifice at the LPG cylinder due to excessive flow. If it senses too much flow it will almost completely block the orifice allowing only a tiny bit of LPG through.
Turn the cylinder or cylinders off and wait a few minutes. Open the valve again but open gradually for the first bit. That should allow the LPG pressure to stabilize.
Do you know that it is recommended that all RVs get a LPG leak down test annually? You should also put a manometer on it and check the pressure regulator. Read here;
http://www.rverscorner.com/manometer.html
