Why does my 2006 RX330 vibrate between 20 and 40 mph?

What is your question?

It seems to vibrate when the car is under torque between 20 and 40 mph. I have had new tires put on and the front end aligned.

What makes this problem better or worse?

only at slow speed between 20 and 40 mph

How long has your 2006 Lexus RX330 had this problem?

a few weeks