theres loads of people on here with straight six bimmers with erratic idles,
i was reading th bently bmw 3 series manual and saw this:
"a cracked or leaking pressure regulator vaccuum hose may cause and erratic idle"
ive never even thought this hose to be a posibiliy and if it is it would be a cheap fix to a pain in the arse problem...
thought sombody might want to inspect or renew theirs, ill do it when ive replaced sump gasket and cam chain etc......