I have a new 2006 TL that on four ocassions starts a serious vibration - I mean it scares you-on acceleration. It has happened 4 times, always first run of the day and during moderate to severe acceleration. It feels like your are on an extremely rough road and the vibration is a steady rythum.

It has scared my wife so bad she won't drive the car and wants her toyota back.
The dealer says unless he can get it to act up he can't determine what is wrong and this only has happened 4 times in 5000 miles. Any suggestions? My thoughts are it is something funny going on in the torque convertor.