Aggggghhhh. If it's not one thing it's definitely your Range Rover.
Exact same as mines has started doing. Ironically after commenting on here about LPG being reliable.
So, pulled up at hospital, could smell the LPG, switched off, got out and could hear the hissing, great. Left it to depressurise whilst I got my Physio, had a look and I could see one of the hoses was loose. I thought I'd get it when I got home as Hospital car park isn't the place to fix your motor.
Anyway the car started then cut out, about 4 times before it fired up. Then it was lumpier than a lump thing. Cut out a further 5 times. Eventually, giving it a few revs, you could hear the engine note change and she ticked over sweet as a nut.
Hose repaired, checked for more leaks, found none. Sometimes she's fine other times lumpy. But just now I went for Gas, just before I stopped the engine light came on. Petrol was low, light on, half a tank of gas still. Struggled to start at the petrol station, again a little lumpy, not as bad before, switched across to Gas and was purring like a Lion

Got home, turned her off, then fired her up and she was fine.
The wife has just informed me that it was running funny with her on petrol a few times the past week, nice of her to tell me!
Anyway, I'll leave it to see what happens before the panic sets in lol