I have this slightly. My plan is to do the IVM (IVC) forget what it's called. It's that power distribution box in the passenger side of the under hood compartment. Also will do all 4 vanos solenoids in the near future. I've read that both of the above contribute to better/steadier/higher idle and so will be doing them as PM even though the 4.8 is driving great according to my right foot and lack of codes being shown by the ECM.

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2005 X5 4.4i Build 04/05 Maintenance/Build Log
Nav, Pano, Sport (Purchased 06/14 w/ 109,000 miles) (Sold 8/15 w/121,000 miles)

2006 X5 4.8is Build 11/05 Maintenance/Build Log
Nav, DSP, Pano, Running Boards, OEM Tow Hitch, Cold Weather Pckg (Purchased 08/15 w/ 90,500 miles)

2010 X5 35d Build 02/10
Nav, HiFi, 6 DVD, Sports Pckg, Cold Weather Pckg, HUD, CAS, Running Boards, Leather Dash, PDC, Pano (Purchased 03/17 w/ 136,120 miles)