Was the point gap closing down? That would explain a lot; you may not need to adjust anything. Note that when you increase the point gap, you also advance the timing, so recheck that.

The adjustment on the computer box has no effect on plug color while driving the car. If the plugs still tend to foul and you know fuel pressure is correct (right around 28 lbs.), the prime suspect is the water temp sensor, which is the one at the right front of the head right next to the aluminum cylinder with the rubber hoses. Make sure the wires to it make good contact.

Only after you're sure the car is tuned right when driving should you adjust the computer box. Simply turn the knob for the fastest idle speed. If something else is still wrong, though, you'll end up with an incorrect adjustment.