Something similar happened to me, it would feel like the car is getting a chill, brief shudder while in drive with my foot on the brakes. The dealer first said it was a fouled plug, second time they said it was a bad coil, the last time they said it was the transfer case and swapped it out. So far about 3 weeks in and no shudder, gas mileage is a bit better now as we'll.

The SA at the deal and my Indy Shop said to start off by replacing the spark plugs and the coil packs. Ordered these yesterday from Amazon - all together it was $195 and change for these (NGK Plugs and Bosch Coil Packs).

Additional info: the car is in drive or reverse when this happens and it doesn't do it until it has gotten up to operating temperature.

...pointing more toward the AC cycling?
And I'd love to find the 74 deg spot you are talking about. It's freaking awful hot & muggy here lately.

I've ruled out the AC cycling - I can feel that and know it's normal. I replaced all 6 spark plugs and ignition coil packs today. Unfortunately I haven't been able to driver far enough yet to determine if this has fixed the idle dip.

The 74 degrees was actually north of New Bern near Grantsboro and Arapahoe, NC.

Update: I probably drove 75 miles today - interstate, city, stop and go with traffic. It didn't give me the idle dip at all and the engine is running much much smoother. I'm guessing it was a spark plug.

Arby -

I'm having the same issue with my MY08 X5 3.0si. I've changed the valve cover gaskets and the spark plugs but the idle dip is still occurring when car is in Drive and foot on the brake. Was curious if changing the coil packs fixed the problem. Thanks.

My 07 3.0si is doing the exact same thing. I may need to swap out the plugs and coil packs.

I ended replacing the coil packs and this seem to have fixed the idle dip problem. It's been 500 miles and still no issue.