Sometimes recently when when I start the car cold the it does not want to idle, the computer will try to correct and I've got to give it a good rev to get it to idle smoothly. Also when I'm driving and I get off the Gas to decelerate the Rpm's will dive down to 300 or so rpms and shoot back up to where they should be.

This sounds like a Vacuum thing to me but what do you think?

It is a 2000 1.8 auto

 

I noticed with my 2008 M3 2.0L 5spd when i start my car when its cold the rpm's will fluctuate and have like a hard time keepind a constant rpm and then it will work its way to almost at 2000 rpm and hold there untill its warmed up a little bit then drop right below 1000. maybe this is the same problem?

 

Hi! Can anyone give advice as to why the RPMs in my 2005 M3 jumps all over the place when I decelerate down to about 1000 RPMs? I've had fuel injection cleaned and spark plugs replaced. No change Any help would be sooo appreciated! Thanks!