Bad plugs, wires, cap, rotor/points can make a motor do funny stuff.
With all that carbon build up, it sounds like it is a timing or fuel problem. When you had the timing adjusted the first time, it may have helped, but with the mixture of carbon, bad wires, and crusty points, it may be wigged out again.
I'm far from an expert on this stuff. It sounds to me like you're checking the right stuff.
