It's been a whilse since I've needed to look at this stuff, but are VanAaken developments still around or even MA developments as they are not that far from you, there is also redline racing, or even just a local rolling road to have it checked out?

Be careful with the whole AA thing, as it will depend on what cover your other half has, they may just recover it to the nearest garage.

I assume you have tried another metering unit as it could be over fueling a huge amount casuing the missfire?

I'm only down the road from you in Ottershaw, so could follow you to a tuner on a Saturday morning and bring my towing bar with me just in case, if you need my help then send me a PM as I will forget to come back and check this (I'm old!)

Good luck

Rich