REG633

Hello everyone, I have a 1984 633csi, that idles ruff, no acceleration from a stop, and has black smoke coming from the tail pipe. If I can get it up to 60 mph it runs fine until you step down hard on the accelerator, then it bogs until you get off the accelerator, but once you come to a stop it idles ruff but will not accelerate, it just dies out. I need some help please !!!