Car was running smoothly, till last week, was driving at 120km\h for about 20 km, after stopping for a wile, car was switched off, when i switch it back again, it won't idle, could only idle with accelerator, can drive, but when stop it switches off, took cylinder to engineering, got it fixed and fitted back on car, only drove for about 30km, then the problem start again, but if i take a pipe that delivers air from cylinder top, to injector mainfolt, car can idle, but idling is rough, car can only be driven without switching off, but it produces black smoke, what mite be the problem? as car only idles if i removed one air pipe from the injector mainfolt, either the one from the cylinder, or the one at the back