V8 LPG Disco dying for no apparent reason

My Disco has started messing me about. I have been using it happily since getting it back having sorted out the leaking timing cover gasket. It has a new starter motor and battery. I had been to the cinema with the family. We had driven there OK and had been sat for a couple of hours. I started her up and drove a couple of yards and it died. It turned over happily but was not firing at all. I switched it to petrol and tried again. After letting her stand for about ten minutes it started. Drove home ( about 20 odd miles) she conked out again for a few minutes and started again another three times. On each time there was a loss of power and the engine just died. This was running on petrol ( I am aware that LPG can freeze up in the cold and it is cold so was on petrol)
Any one got any ideas?

Hi, sounds very fuel pumpish to me - perhaps this is linked to the cold.

yeah, i reckon the lpg system is knocking the injectors off, check wiring is ok. i cut a few (then soldered em back together) to see what the state of the copper core was. a bit green on some of em so i had a real ferk about sorting them!!!

Ta
I have had her running today for the first time since the 21st and she ran ok on petrol. Weird !!
Ta for the thoughts

what year is the disco could be the spider.

I had similar sounding problem on my 95 v8 disco with lpg.If I let the gas run out it would not start on petrol for about 20 minutes.On close inspection I found there is a rubber band on the air intake before the plenum chamber this had perished/split I bodged this using a rubber glove and cable tie.phoned lpg dealer for a replacement which never came,Disco working fine with bodge up for last six months,I believe this rubber band is some sort of anti backfire device,

She is a 96 3.9. Interesting about the rubber band theory. When I first got it it backfired on quite a few occasions. She hasn't run out of LPG but she does get low. I will have a look for this rubber band