P38 , 4.6l power loss and popping.

check fuel pressure as lpg conversions notorious for shagged fuel pumps where people run them dry

Fan speaks sense. Mine pops and farts when its about to run out.
Also, just realised my comment proves yours lol.

Thanks for the input.
I have cleaned the MAF with carb cleaner and put it back on.

It now runs almost perfect on LPG but is still pretty rough on petrol.

It is worst when cold and seems to lack any power from a standing start, idles at just under 500 and feels like it is ready to stall but doesn't. It pops a lot on hills at low revs and isn't until it gets warm that it starts behaving.

Now as LPG is ok and petrol isn't then I am assuming it has got rid of ht leads and fuel pump out of the equation.

Having read other threads on popping and rough running I am wondering if I would be advised to reset the additive values (not sure if this is correct) and does this mean finding someone with a laptop?

Fuel pump isn't out of the equation as LPG doesn't use the fuel pump.
Probably fine to assume the leads are fine tho.