1986 Ford Mustang Rough idle

My 1986 Mustang LX idles rough and blows black carbon and smoke. I have replaced the O2 sensor, Throttle position sensor, installed carb kit and anything else the mechanics have been suggesting. On a whim, I replaced the original carb with an all mechanical one that just happened to bolt up and the engine runs more like it should. This old carb is filthy and full of crud and doesn't provide a good spray pattern, but it works good enough to make the engine run smooth and without the black smoke and carbon. My guess to the root of the problem is its in one or more of the sensors or electronic controls for the fuel mix. I have run scans on it with a "auto X Ray" from auto zone and received several trouble codes from MAP to every control in the system. Sometimes it scans, sometimes not. Sometimes it says "vehicle not responding". Am I correct to assume that if one of the sensors is out of whack, the computer tries to compensate and make adjustments to other componants therefore throwing them out of their normal operating ranges? What would you guess my problem is? Sure would appreciate any advice you can give me.