Your shifting problem is probably not vacuum related. The problem is called 'stacked shifts'. If you search on that term, you will find information. It's possible that you can resolved the stacked shifts by adjusting the bowden cable. A search on 'bowden cable' will bring up lots of info about adjustment.
Vacuum controls the harshness/softness of shifts. The bowden cable controls the shift points.
I didn't think the 82 model had a throttle plate. Perhaps it does.

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13