[Rob1796]

I have a pretty decent level of experience with the M54 and S54/S62/S85 motors, and almost as much with the N54, but not much at all with the N52s (I don't really care for it as a motor). So I'm coming to you for some help.

My wife has an 2008 X3 3.0si with around 78k miles. She had an issue last year where the dealer explained that a valve spring had worn down, and as a result the valve itself slipped and bent. Long story short, we ended up replacing the entire head of her motor. Her car was running ok for a bit, however around November she started complaining about her mileage getting worse. I wrote it off as the gas stations around here just switching to winter blend.

The other night I took it out and I noticed on start up it was hunting for idle. Not bad, but very much noticeable. Then today when I was standing outside the car and she started it up, I could clearly hear the car trying to smooth out. It doesn't sound like it would with a bad coil pack (and we had all six replaced when we did the head last year). I just ran some injector cleaner through it (RXP), but it isn't an issue the car experiences warm so I don't know if it just has some dirty injectors.

Has anyone experienced anything like this (Google searches haven't been my friend on this one) and know the fix? I'd like to think it has nothing to do with the new head. Also, it doesn't sound like the lifter tick I've heard in other BMWs.