Look carefully, with a flashlight, under the intake. Make sure all of the vacuum lines are attached to their ports. Should to 2 maybe 3 on the left side of the body and one at the front. If I recall, one of those on the side is actually just a tad to the rear of the others.
If any are loose, all you need is a 12" pair of needle nose. They will let you reach way back under the intake to slip the rubbers back on the nipples.
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72
'02 CLK320 Cabriolet - wifey's mid-life crisis
2012 VW Jetta Sportwagon TDI...at least its a diesel
Non illegitemae carborundum.