I still think it's the fuel system.  If you haven't changed the gray fuel lines, you will have a green goo throughout the fuel system, which cloggs fuel filters, especially in the carbs.  This will cause the ski o run lean, and starve for fuel.  This is dangerious because evntually you can burn up the motor.
Since you don't want my advise I am backing out of this thread.  Maybe someone else has another idea.
Lou