A broken or disconnected vac line will cause all sorts of idle problems -- miss, vibration, hesitation, and harsh transmission shifts. Plug the line if you cannot find what it goes to.
I cannot load the pic, so I cannot tell exactly where the line goes. What color is it, and does the plastic line have a color stripe also?
The sensor is just for use with diagnosic equipment plugged into the X11 connector on the firewall, I don't think it is connected to the in-car computer at all.
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!