OK, updating. The X is still running like crap, particularly after it warms up after 2 or 3 minutes, and especially when you gun it for power after pulling out in traffic, or if going uphill. Sometimes after gunning it, it seems to start missing and running even rougher. I pull over, shut the engine off and restart, and it smooths out some.

So, I've changed out before-CAT O2 sensors, the CATs, the MAF sensor, and removed & cleaned the VANOS solenoids. The CIL has stayed off since cleaning the VANOS, but it still runs bad. I cleared all codes and rechecked. I get a P0305 (Cyl 5 misfire) ("Pending") and a P0420 & P0430 (CAT Bank 1 & CAT Bank 2) (both "Permanent").

The Cyl 5 misfire is weird. I hadn't been getting that until recently, and it doesn't seem to miss at idle, at least not most of the time. Maybe a coil issue. I'll try swapping a couple of coils around to see if the code moves with the coil. (If I remember right, the code doesn't always indicate the correct cylinder, sometimes maybe the one next to it.) Pulled all the plugs, they're not fouled, but all have gaps now of about 0.055 - 0.060. Spec is 0.044, so I got all new ones and will probably install them tonight.

I also have new after-CAT A/F sensors, but haven't installed those yet. Will probably do those this weekend. Was gonna do this past weekend but all my free time went into replacing the valve cover gasket, which was leaking badly. At least that seems fixed.

I've recently learned that these engines have these "DISA" valves in the intake manifold that often cause havoc. I've ordered new ones, along with the Y-configured PCV or whatever kind of vacuum hose it is. Not sure if I'll have to pulll the intake to do any of those, so those will probably be last on my list to try.

Don't know anything else to try, except maybe try doing a better job of cleaning the VANOS. I keep praying though, cause I gotta solve this! Arrrrgh!

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2009 X5 3.0
2001 X5 4.4 - Sold