vr6 miss fire help please it's doing my head in

Please if anyone has any info on this it would be a great help.
My golf has a miss fire it's only doing it under load and under 2000rpm.
Engine spec is this.
2.9 vr6 bottom end
263 cams
schrick inlet
abd intake & induction
milltek exhaust inc 6 branch

What we have done so far is this.
maf (genuine)
coil pack (genuine)
leads (magnacore 8mm)
plugs (not sure what he used but they are new)
injectors (genuine)

It has no codes on vagcom.

I really don't know what to do next. I called stealth tonight but they can't look at it till september and it's really doing my nut in now.

Anyone got any ideas?

p.s it only does it once up to running temp never when cold

Did you ever get this sorted??