my car started to have rough idle a couple of days ago. I searched this site and have removed the air cleaner housing and inspected all vacuum lines that I could see, but could not find any that is disconnected nor any that would appear to be broken.

Let me be more specific, perhaps it will narrow down my symptoms:
1. rough at idle
2. appears to run normal as it approaches about 40 mph.
3. Trans shifts normally
4. gauges appear to function normally ( idle at 600rmp, oil at about max during idle and in gear)
5. starts normally.

thx in advance for your help.

emmy
91 560 sel