At 500 rpm it should idle smoothly even if that is a little low. Yes, those are pages from the E30 Bentley Manual. You REALLY need to get one. Erratic idle is almost always vacuum- leak related.
Quotes to live by:
guessing gets expensive
nothing is more expensive than a cheap BMW
Ken Kanne, Silverhill, AL, Honorary Forum Grandpa/Craigslist addict/Hoarder of all sorts of stuff
1995 318is "Bebe"; 1993 325is "Elvira" 1985 635CSi "Katja" 1984 633CSi "Sylvia"
I NEED A NAP, DANG IT!