I would clamp the PCV hose and PB hose with vice grips with a rag to protect the hose from the serrations & retry it just to elim those vac leak potentials. got another carb you can borrow/sub in for an hour to test? that would confirm/elim the carb but that'd be my guess (carb) expecially with it being P/T & that severe. Is the linkage hanging up anywhere?