You have a vacuum leak someplace that is affecting all those systems. Now it's just a matter of systematically going through the car and Isolating the leak. Start by taking a look at these vacuum diagrams, yours will be very similar to the 300D:

Vacuum Diagrams

Once you know which line is which you can try blocking off parts of the system to determine where the leak is. If you do a search on vacuum leak hear you will find lots of info.

I don't know of any light blue lines offhand, but if you post a photo, we can probably tell you what you're looking at. There is a black vent line that's supposed to be open under the dash, but that's the only one I know of.