Perhaps a short history lesson will help. Drop back about 6 or 7 years, and motors ran great. But sloppy. They dumped a lot of excess fuel overboard into the lake. By the time yours was built, public and gov't howl forced mfrs to try to clean up their motors. On yours, they rerouted the dumping into the cylinders for supposed burning. In truth, they were still sloppy, but ran poorly. And fuel still went into the lake, but at least now it was black fuel instead of raw gas. And wet plugs were a curse. Actually, the wet plugs aren't all that bad. It should run even though.
In all fairness, cars ran crappy during those years also. They called it "smog control".