Ok, so I replaced the vacuum hose, which didn't help. Then I changed the plugs. The old ones had some white residue, but looked ok otherwise:
Then I used a timing light for the first time in my life, haha. Not sure if I did it right. I plugged the vacuum line and with the engine warmed up it looked like this:
Which looks like 16BTC to me. It smoothed out a bit around 12BTC. I think I checked TDC when I replaced the timing chain, but I'll check again.
I haven't really driven the car yet, but I will tonight and see if it idles better.