[strelnikoff]

Only happens at speeds of 20-40 mph and car is coming to a stop (foot off the gas pedal). The idle will fluctuate between 800-1000 rpm. Seems to happen only when the car is wormed up (about 5 mins into driving). Now here is the kicker: it does not happen when the A/C is ON! With the A/C ON, the idle speed does not fluctuate in that speed range. This weekend I replaced oil separator (CCV) + separator vacuum hoses. I have also cleaned the icv and throttle body. Need help, this is driving me nuts!!

 

[im]

a/c raises the rpm's.
possible vacuum leak.
or
the fuel filter?

 

[SJBimmer]

a/c raises the rpm's.
possible vacuum leak.
or
the fuel filter?

Might want to check all of your pleated air intake parts for a leak. Check the parts very carefully, esp. in the pleats. The cracks like to hide. Although I cannot be sure of course, these parts are a common failure point, and it costs nothing to check. If you have a check engine light get the codes read. This should help point you in the right direction.

 

[strelnikoff]

Turned out to be vanos oil pressure hose. there was a vacuum leak where the hose was crimped at the factory. replaced the hose this past weekend. the easiest way to get to the lower part of the hose is from under the car. fixed the idle issue + got my torque back. :thumbup:
hope this info helps the next guy.

 

[SeanC]

So one end of this hose goes into the intake elbow, right?