engine wants to stall when hot

What is your question?

I replaced the mass air flow sensor the check engine light went out and it runs better. When I start it when it's cold the idle is good and it runs fine. When I stop and start it when it's hot it wants to stall. I have to hold the accelerator until it gets to a proper idle to drive. Could it be a cold start valve or oxygen sensor. It blows black smoke when I start it and when I accelerate.