Originally Posted by
andyjg79
need a bit of help
runs fine under normal conditions
but on full throttle have teribble miss fire
let of the throttle a touch black smoke then its of
changed leads plugs dizzy cap arm
had turbo problem put a nother one on since then i have had this missing
smells like it is running slightly rich as i am taken her to spec one over the weekend any surgestions would be great will leave it with you all
many thanks in advance

You sure its not overboosting and the chip is cutting it out, thats why when you back off you get all the black smoke of un-burnt fuel.