help please to much fuel

my p38 has just decided to over fuel i think for no apparent reason she has started missing and turned 7 out of 8 plugs black. ive changed plugs,air filter and usual service parts but she still no better.can anyone out their help with any ideas what could be the problem ,cheers

Get it onto some proper diagnostics ASAP. Good chance you have a failed O2 sensor but given cost of symptoms (high fuel usage) and fix (new O2's) the cost of an hour on T4 will pale to insignificance.

it was on lpg but that started playing up so ive disconected the power and taken the mixer off because she had a big backfire it ran ok on petrol after this for tow days now this problem could this o2 sensor still be the problem

The backfire could have fried the MAF but this is just guessing. You need to get it onto diagnostics.

I think it could be the Maf blown up by the backfire, but agree with JT, get it on diagnostics cos running it could do real damage, did it blow up the airbox?

ive had the old girl plugged in and was told shese not as wired up as i thought and was advised that the best plan is to get back to basics ,s0 i tried disconecting all the sensors individualy and they made no diffrance so ive come to the conclusion that it may be the coil pack.when u first fire it up its ok but when she gets to temp she starts missing?