I dunno. I’ll reference factory manuals when I get home. I replaced the sus vacuum cap and it made no difference. The vacuum line from the distributor to the carb is fine, no cracking or anything. Still need to replace the one from the big red cap to the air cleaner though. Nobody has 1-1/4” line.
That bolts to the exhaust passage for the smog pump in the head. It should not have a breather on it. It should be blocked off. That could be a lot of your problem right there.