Recreational Vehicle Lpg Tank Valve/gauge problems of the 1999 Jeep Grand Cherokee

Vehicle stall's while driving regardless of speed, outside air temperature. . . Engine temperature etc. On some occasions if I slip it into neutral I can restart but mostly I have to pull to the side of road and wait a few min and then it starts. . . The vehicle is well maintained and I have spent thousands trying to resolve the issue. I have had the pcm, cel, relays, starter, alternator, battery, fuel filter (in-line), electrical system diagnostics, tune up, oxygen sensor replaced. . . Dealer and my regular garage are stumped. There are thousands of posts on forms on the internet complaining of the same issue!!! it seems to me this is quite dangerous at highway speed with no forewarning the gauges sling cw then ccw to zero rpm and zero mph although still coating at hwy speed you have no power steering the car is off. . . Note it can stall just after starting while stationary or moving or 1/2hr later or more I might stop for something (gas, groceries etc) car running great come back to the car and it wont start. . . Iit seems totally random! note this 1st started @ 140000 miles and is still occurring 5000 miles later. . . Sometime it will drive fine for a few days sometime it stalled at least once while driving. . .