Since the symptoms are that the carb is dumping gas into the manifold, I would chase that down first. Could be that the fuel pump pressure has jumped for some reason and forced the float level way too high. In that case it wouldn't idle well or at all. Repop 6-cyl. fuel pumps are notorious for this. I would check the FP pressure and look down the carb for flooding if you can get it to idle. I's also possible that there are two problems, high pressure and a leaking pump diaphram. Ethanol gas will attack some old rubber used in pumps.
