Fluctuating neg. to ground on ignition coil

I have used Rislone in 2 ways:

• With the engine revved up, very, very slowly dribble (pour a bit at a time) 1/2 can down the carb throat to help clean intake valve stems and valve faces. It will make a LOT of smoke. (That part is fun LOL)
  
• Put the rest in the oil to help clean all the valve stems.

It may help, it may do nothing.

If your change in the spark plug wires helped the engine to run smoother at highway speeds, then that may indicate that your issue is in the ignition system. You still need to recheck the spark plug wire resistances. Don't rule anything out.

Is the timing with a timing light steady, or does it jump around?