Ford Repair: 93 ford ranger miss, fuel pressure regulator, catalytic convertor

Question
93 ranger 4.0 started missing out of the blue.  The engine will sometimes run smooth then will start missing and running rich....black smoke from tailpipe.  When this happens the voltage gauge will start bouncing from high to low, then when voltage settles in missing stops. any ideas?

Answer
i would think voltage is jumping because of rpm change in skipping engine if not check battery cable connections at battery and engine.

you could have leaking fuel pressure regulator intermittently. bad spark plug-plug wires-coil etc. don't waste to much time if you can't figure it out because when you are getting black smoke you can also get unburned gas in your oil and catalytic convertor causing expensive damage. good luck.