please help before i tear anymore of my hair out. p38 4.0 v8 with lpg just had head gaskets done and rebuild done now car wont run for anymoe than 10 to 15 mins and cuts out as if the fuel has been turned off it does this on both gas and petrol have tried every combination i can think of turned the gas off and it still wont go, starts great and runs well but only for about 10 mins you would think that someone was sneeking up and turning the fuel off lol, after it cuts our if you let it sit for about 20 mins it starts fine but after 10 mins orso it cuts out again. can anybody help please as its driving me mad ive been at it this past 3 weeks and cant figure it out thanks

Sounds electrical to me.....check the engine earth straps, security of the Coil Packs and wiring, check the security of the power connections to the fuse box....

Another likely culprit could be the fuse box - give it a sniff, if it smells burnt or warm, it could be warming up and expanding causing all sorts of electrical niggles....change over the 1gnition relay for another one of the same colour in the fuse box as the relay could be breaking down when it gets warm!

Also worth looking at the crank and cam? sensors but would need diagnostics or a scope.