Stumble issue

Ok so I hooked the vacuum advance up today and had no change, still stumbles off the line. Checked the accelerator pump and looks good, shoots plenty of fuel. I also thought I would try heavier springs for the metering rods in the eddy carb but when I pulled them out, it already had the heaviest springs in. Not sure what to do next. Also i took it for a drive and punched it and when it shifts into 2nd it boggs and falls on its face. What would cause this? Thanks for the help guys. Hope to get this figured out cause this thing feels like a torque monster.