Vacuum Leak?

I have an FBO distributor and module too and I've had the same symptoms. It's very annoying and frustrating. I haven't really had a chance to try out different things, but I have read that the vacuum advance tube should be connected to the intake manifold with the FBO system and the carb port should be capped. Everyone says connect it to the carb, but FBO says differently for some reason.

I'll be reading this thread to see how you're making out K3522.