Thanks for the tip, Brian. I tested my vacuum at the vacuum control valve, after the little plastic can the manual calls a damper. It was right on at a little over 10 inHg. The manual specifies 385mbar +/- 25 which converts to 10.6 to 12.1 inHg. So what should I be reading if I tee in where you suggest? How do I know how much to tweak the screw? I also was wondering about the "restrictors" as the manual calls them. I think these are the same as the "orifices" some people talk about? I am not sure I have a proper vacuum diagram in my factory engine manual for my particular engine, since they all seem to include the air recirculation valve, which I don't have. I am not sure therefore if I should switch my orifices to match the colors in the manual diagrams. Anybody know the proper colors for restrictors/orifices for an '87 300d with no air recirculation valve? The restrictor I currently have coming off the vacuum control valve is green and the diagrams I have specify blue...

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87 300D 162,000 miles: It's not just a car, it's an adventure!