poor starting when hot

[andy & fonz]

Hi
after leaving z3 2.2 standing for about an hour when hot temp gauge needle in the middle, when starting starts but revs about 2/300 very lumpy touch throttle clears with a cloud of smoke from exhaust, runs o.k obd tells me misfire on 3 and 4 cylinder remove plugs number3 a little black number 4 very black all others look good, fuel filter changed air filter ( k&n) new maf new (siemans) plugs been in about 1000 miles the black on the plugs is dry have swapped coil packs around no change, mind you do's not do this all the time, if only left standing a couple of minuets its fine, I am convincing myself its a leaking fuel injector, unless someone knows better listing to them running through a screwdriver they are all clicking not using any oil milage 615000 help its driving me crazy!
thanks for the feedback

[NZ00Z3]

I agree with you, sounds like leaking injectors.