01' 325i RPMs still drop after some maintenance

[BMWeiß]

So for the past couple months I noticed a rough idle coming to a stop and just in general (dipping below 500 then back up to 6-700), so I cleaned my ICV, MAF while I was at it, and just today replaced plugs.

I've watched it in every instance that I can when putting in the clutch, and it is still dropping down and then back up, except now at least without shuddering or sounding like its bogging. Not sure if it would do anything but also tried disconnecting the battery for any sort of reset fix.

Currently at 169k miles. Any ideas on things to check out?

[Honolulu]

I think the fuel/air mix is all to c*ck, specifically much too lean. You're looking for an intake leak which may/not whistle at you (literally, they sound like that). Or a smoke test by a pro.

Also, of course, there's "Mechanic's Rule": look at what you did last.

Anyone else?

[BMWeiß]

Don't know how but I forgot to add that I have a P0455 code (didn't think it could be related), and when filling my tank gas manages to leak to the ground (which my shop mentioned a smoke test for). Does this tie into the fuel/air ratio issue?

Also an intake leak may be a part of it because I have noticed a slight whistle when pushing it before, just didn't think too much of it.

[dworthy]

Yes, a leak in the Evap system will cause you to run lean.

The most common culprit for leaks is the Upper and lower intake boot. Most cannot see the lower boot leaks as it is way down in the car, as the upper is much easier to see. Next will be the CCV system, as by now anything that is plastic if very brittle so check that too.