I get that stumble on 8N and also geo metro w/throttle body injection. The best carbs for not having that characteristic are the slide type with vacuum dampener, motorcycle type.
What happens with your N is, when the throttle is opened suddenly the air fuel mix goes lean for a moment, till the velocity of the air increases and draws more fuel. Of course the engine has to speed up for that to happen. It is somewhat the nature of the beast, worse when cold. As you describe it, doesn't sound like much more.
Cars used to have accelerator pumps that gave a little squirt of gas when you stepped down on the throttle. If you advance your throttle slower it should help.