Pull the plugs right now and look at 'em. If the porcelain is white, fatten up the mixture. If the porcelain is dark gray to black, lean the mixture. If the porcelain is the color of a cigarette ash with a hint of brown, the mixture is right on and something else is wrong.

There is way more to tuning a motor than this short paragraph, but I'm just trying to catch you before you hole a piston if the mixture is real lean.