40 hp ignition problem

[DK_BOE_SR]

i have a mariner 40 hp "e" series 2 cyl, single carb, electric start w/rope also sreial # 676bs105010 that stumbles or drops a cyl under accleration. will eventually pick it back up. new plugs, rebuilt carb, new fuel pump, hard bubble at tank. question is can the cd pack be weak and dropping a cyl under accleration?

thanks for help
dave