'84 528e major problems-please help!!

[srmarshall]

I have a 1984 BMW 528e-5 speed. The problem I have occurs intermittently, usually within 5 minutes of starting the car, then clears up and the car runs fine, making it very difficult to diagnose. The car will start fine, and then it will begin to sound like it is not running on all 6 cylinders and will stall. To prevent it from stalling, I rev the engine and black smoke comes out of the muffler, along with a strong smell of gasoline. The car will run rough like this, with the engine revved, for a few minutes. Then it will smooth out, and usually doesn’t occur again until the engine has cooled. Also, the SI light on the dash is always on, and the indicator ‘check’ lights for the oxygen sensor, etc do not light up when the “check” button is pressed. I’m not sure if either of these are related to the problem, but any help you can provide would be greatly appreciated, as 3 different mechanics, including a local BMW dealership, have been unable to diagnose and fix the problems.
The following parts are among those that have been replaced within the past 3 years in an effort to fix the problem:
Fuel Pump – Master and in-tank
Fuel Pump Relay
Ignition Coil
Spark Plugs/Wires
Cold Start Valve
Thermal Time Switch
Distributor Cap
Distributor Rotor
Thanks for any help/advice you can give me!!