Sputtering is a sign of a misfire. The unburned fuel will burn in the catalytic converter and overheat it. The black smoke from the tail pipe is proof of too much fuel going into the exhaust system. If the catalytic converter isn't damaged already, it will be if you continue trying to drive like this. Once the catalyst melts, it will block the exhaust system. That can lead to what sounds like a backfire, but if the engine is otherwise running properly, the clue to a plugged catalytic converter is a smooth and steady hiss from the tail pipe instead of the normal "putt putt".
If there's no diagnostic fault code, how did you determine the mass air flow sensor is "malfunctioning"? What exactly do you mean by that? That sensor is the main one for determining fuel metering calculations, so if it's reporting a wrong value, you're going to get the wrong amount of fuel.
Saturday, September 19th, 2015 AT 9:15 PM