The X5 has different pressures for the TC lockup when in sport mode vs normal mode. When i first noticed the issues, it was only in normal mode, sport mode was fine because it maintains higher pressures in the valvebody. After a few months, I'm getting issues arising in sport mode, like the shuttering. Also, you will likely notice that cruise control eliminates the throttle oscillation (misfire feel) because cruise locks up the TC so the trans is not locking/unlocking trying to maintain speed. If I'm in cruise, all issue pretty much disappear. I have a 4.6is and I was getting consistently avg 16mpg but now i'm around 15.4, same driving habits.