Has anyone checked. The fuel reg. It has a rubber diophram in it that can go bad and srrart to dry up and leak fuel. Iit happened to me. It spit out black smoke and raw fuel ran like crap. Had it towed into my mechanic and he knew what it was right of the bat. It toasted the cat. Converter but that was an easy fix. Im not sayin this is your problem but it is the only problem i had with my 86.