Avs2 650 tuning on a 340

Whether the vacuum advance is hooked to ported or manifold vacuum has ZERO to do with your problem. If you go running down that rabbit hole before you actually find out what's going on, you're going to lose yourself even further. I don't know about the rest of these guys, but you're getting closer and closer to this being a waste of time if you won't listen. We're trying to tell you how to diagnose this as hard as possible. It seems you're trying your best to do the exact opposite.