Resolved?

If not.....Any codes?
At Idle take you hand and place it in front of the each exhaust tip. Which side is giving you the stumble?
Tip: Double check your plug gap on the NGK Iridium IX as it should be 0.044" and make sure all the small wire connectors are tight at the coil tops. Make sure the coil boot is on the plug not next to it in the hole.

There is always small chance of a bad new plug. Reasons: Poor handling anywhere in the distribution supply chain path and of course by the installer/DIYer. The manufacturing process quality control has approx .0001 to .001% failure rate. Most are installer errors sent back as defects. Seen one too many over the years.

Report back.

__________________

2005 X5 4.8IS
The Blue ones are always FASTER....

Current Garage:
2005 X5 4.8is
2002 M5 TiSilver
2003 525iT
1998 528i
Former Garage Stable Highlights
2004 325XiT Sport
1973 De Tomaso Pantera, L Model
1970 Dodge Challenger T/A 4 sp Alpine White
1970 Dodge Challenger T/A 4 sp GoManGo Green
1971 Dart Sport, “Dart Light” package
1969 Road Runner 383
1968 Ply Barracuda 340S FB Sea-foam Green