I am trying to tune my straight six. I think my carbs are too rich. The reason I believe this because when I put the pedal to the floor it stumbles really bad. It also loads up at a red light and starts to smoke a little. The final thing is when I take the vacuum line off the distributor and leave the line uncapped, the engine runs better. Plug the vacuum line with a screw or bolt and it slows the idle down. Any ideas?