Serious help needed

My 89 420SEl is still missing and quitting. I have been through the plugs, wires, cao, rotor, fule pump relay, ovr, o2 sensor and the motor still quits.

The check engine light comes on and it sputters and eventually dies.

I did hear something today at idle. There is a mechanical clatter before the egine dies. It is not a valve or chain clatter it sound like a computer generated clatter at the front of the engine, the idle goes up and then it quits. Again all while the check engine light is on. Does anypone have any suggestions? I have apparently missed someting here that I can't figure out.

Thanks,

Dan D