I know a little vibration is normal here, but when I come to red lights, I often find myself shifting the car into Neutral because I find the vibration while keeping it in Drive a bit excessive and annoying.

If there is a problem, what would the culprit most likely be? And how big/expensive of a job is it to fix?

'08 IS250 AWD, 92k miles

Thanks!

Check your idle first to make sure it is correct. You might have to clean the throttle body. If the idle if within specifications your motor mounts are going bad.

I see you have a 250 so it may be carbon build up. Do a search and a few threads will come up

There's a TSIB or whatever they call it now for a rough idle when your engine is already warm. I got it in the mail, but I can't recall what the number was.