8v Cutting out when hot ?

[mk3gti]

hey guys and girls got a "J" plate Mk3 8v with a very intermittent fault IE. happens once or twice a month at the most, tho still very annoying! when driving until the engine is hot the car will cut out at idle and or when the clutch is fully depressed it wont then start for a minute or two and when it eventually does quite a lot of smoke pours out the back?!? as its such an intermittant problem im not sure what to try first ?? any tips would be great? cheers!?

[Optimus Wol]

possible cause of this might be the amplifier in the ignition. all the black smoke is were the fuel is being introduced into the combustion chamber, but not being burnt. when it finally does spark, it produces the black smoke (over-fuelling)

might be worth waiting untill the problem is more consistant though. easier to pin-point then