Lexus Es350 'jerking Hard'

[aske]

Hi all,

I am facing an issue which is irritating with my ES350. I read about 'gear flare' and 'transmission problem' in past threads. I don't know what this classifies as:

Some times, when I am driving, all of a sudden, the car 'sort of jerks hard' - this is when I am accelerating. I am not a hard accelerator - but that jerk is quite hard. This happens around 40% of the time. By 'jerk hard' I mean it feels like the car suddenly pulls back with a sort of a knock.

Can you please help me classify this problem in a way I can explain it to the tech. I am sure when I take it in, he will see no signs of it, and I will not be able to show it because the car knows automagically it is being taken to the doctor :-(

thanks