2006 TL auto. I think it happens more when its cold, but cant be sure.
There seems to be some kind of stumble at about 4k rpm during moderate to hard acceleration. Just a quick little hiccup. The rpm don't flare, they seem to stop going up for like half a second. If I recall, it happens in second gear, at about 45 or 50 mph (around 4k rpm)
If I completely hammer it, there doesn't seem to be an issue.

Any one else experiencing this? I tried to do a search, and got nothing.