All vacuum components are interrelated so a problem in one area will effect another. You'll need a MityVac to trace down the leak. You could disconnect the yellow line under the hood and plug the line it went into. That goes to the doors. If the car shuts off ok with the yellow line disconnected your leak is probably in the door/fuel/trunk system.

__________________
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