Need help! At my wits end.

so your distributor advances 50 degrees? I think thats your problem right there. most cars with that kind of Bild don't even use the vacuum advance system. mechanical time it all in has 36 and see where it idles at before the centrifical kicks in.
It advances to 50 degrees with the vacuum hooked up. Without it is 18 initial and 18 mechanical for 36 degrees total.