Ok, this started after I filled up at a little country store in the middle of nowhere, back in mid January. A week later, I started ripping apart the motor, and everything looked just fine. Upgraded the ignition box, did some other stuff, started her up today, and it still falls flat.
Why did you tear apart the motor ? Was it due to falling on its face ? Did you replace the distributor ? Did you do a compression check before tearing into it? Seems like there could be a lot of variables introduced. Hows the timing curve look? Are you positive the vacuum advance is hooked to a timed port on the carb and not a manifold vacuum port. To me it sounds more like an ignition issue. Do you still have the same gas in the tank you filled in january ? Just trying to place some thoughts and bring out some more info. Especially with the engine picking up when you let off, that increases manifold vacuum which could be pulling the advance and when you punch it the vacuum drops off.