Exhaust is producing black silt what could be the problem?

The car burns air and fuel to run, but for efficiency, the combination must be stoichiometrically balanced. If there is too much fuel, it all cannot be burned, and black smoke/soot is the result. If the car ran out of fuel and was jerking, the PCM was trying to get more fuel to compensate for what it lost, and after you add more fuel, it needs to readjust to bring the air/fuel ratio back to balance. This could take a little while, and all the soot built up in the exhaust still needs to blow out. If it lasts more than a couple days, take it in for testing.