1986 Ford Ranger black smoke

My truck started running bad awhile back. I had black smoke coming out of the tailpipe.I have unplugged the o2 sensor on the exhaust prior to the converter. The 2nd o2 sensor is missing because the converter was cut out prior to me purchasing the truck. I replaced the map sensor, temp sensor, fuel pressure regulator, control module on distributer, distributer cap, rotor, plug wires, plugs, I have checked for vacuum leaks and found none, I added some sea foam to fuel and oil, took choke housing off and spayed well inside with carb cleaner. There is no mass flow sensor on this particular year, at least I cant find one.I replaced the coil with a junkyard coil (seems to get good spark). The truck wouldnt run all that well but the pressure regulator was the last thing I changed. Now the truck runs better but starts hard. It will only start when I push the excelerator all the way down when engine is cranking over. It runs rough for a period of time with black smoke and then runs great when the smoke clears out of it. If I shut it of it has the same trouble starting again unless I let it set for a period of time, then it seems to start easier. Could the fuel return line be damaged or plugged?