No didn't replace tranny - will probably replace my X5 before doing that. The vibration was not that often and as Diyanich noted earlier, it really does not happen in Sport mode or as I also find it does not occur under heavier acceleration so that's my cure for the moment. May result in less MPG but gives a little more FPG (Fun Per Gallon).

I have 02 4.4i with exact same symptom above, took it to dealer and since no code no fix. Did trans adaptation reset and no help.

My thought was the temp sensor in the transmission was going bad, but has not triggered any code but I wasn't going to replace parts at random.

Then.... my upper radiator hose cracked and leaking coolant badly, so I thought well @58K miles it's due to redo the cooling systems, WP, thermostat, Radiator hoses, serpentine belt, A/C belt and walla no more vibration, at least it's hella smoother and pulls harder with less vibration.

If I were you, try flushing the coolant first and see if it improves. I noticed that a couple of years ago when I did the coolant flush. I know it sounds weird but worth a try then you can decide if you want to rebuild the cooling system.

Oh BTW, I had to replace the trans oil cooler as well cause it was leaking coolant afetr my WP replacement just to be complete on my response here.

NOTE, I've been hunting this problem for a while, I even flush my tranny fluild with no affect to fix this problem.

scared me
 

Themmmmmmmmmmmmmm you guys scared me to ever not want to own any Bmw's because I have this similar feeling sometime (a little skipping feeling on the gas pedal: like the car moved-up itself while slowing down on a stop sign.

Skipping, Shudder, Vibration
 

Looks lik I hav the same issue - it has been getting progressively worse and more frequent.

It happns at about 25-35 mph and at around 1500 rpms...not at higher rpms por sped or at least not noticeable.

Also sems worse when going up a light incline.

I was hoping it as something other than tranny.