I fired it up and moved it into the garage today, which was no problem even at 0° Celcius

I then tried adjusting the throttle linkage, but the german instructions I used weren't really suited. I did however manage to get it running sorta right by depressing the IP lever manually.
I'll try to adjust it according to the manual on Thatcher Mathias' site.

And I tested the vacuum in the IP regulator again today, this time while looking at the clock. It only holds vacuum for a dissapointing ~8 seconds.

If it's just a bad seal between the two housings, i will try to smear a little grease in there, and try again afterwards. If that doesnt help than a new diaphragma will be ordered.

But before any of that, there is a) the end of the world, or if a doesnt happen b) Christmas

So happy holidays to all of you