Rough start

when I start my Mazda after it has sat for a number of hours it runs real rough has black smoke and will die a couple times after starting to drive it. And no code lights come on at all.

Perhaps a leaking fuel injector leaving excess fuel in the combustion chamber upon startup. Only way to find out is to have it diagnosed.

thanks would that also make the RPM’s fluctuate drasticaly?

RPM fluctuations are usually caused by vacuum related issues.

the repair shop said they did a vacuum check and found nothing that when they had it hooked up to some machine it showed dirty connectors so they took them apart cleaned them and it ran fine for two days then started back up with a vengance? I just would like to have an idea so I don’t get taken advantage of. So your suggestions are greatly appreciated.