I test drove a 2010 IS 250 again that I've been interested in and noticed that when I slowed down to maybe 5-10 MPH and then accelerated there was on occasion almost a full 1 second lag time between pressing on the accelerator and the car actually reacting and going.

I'm not a mechanic but my first guess is maybe the transmission not catching 2nd gear fast enough?
Is there anyone with a 2010 that can confirm this or maybe give some insight into whether it's an issue or not?

 

Torque Coverter Selenoid and ECT Sensor? Have you had mechanics test drive?