Hey guys i have a 2000 ES300 with 115k miles and has been great since i bought it at 105k miles up until now. Whenever the car has warmed up and i put on on D the idle will for some reason drop from 750rpms to about 500rpm and shake a little bit and after a few secs it goes back to 750 and is fine. When the car is in park its at about 900rpms and then it drops at backs down to 500rmpms and shakes very little. Im want to find out why it would be doing that if you guys can chime in and guide me to whats causing this would be a great help before I start troubleshooting.

I have a 92 es300. My car has the exact same problem, except it has actually stalled because the idle will get to low (it goes down to 500, tries to rev back up, and stalls)
The check engine light is on, and I have found that it points to the O2 sensor on the far side of the engine. I will be replacing this soon, and will give an update.
Good Luck to you!

grab some intake cleaner, and do a search on the IAC valve or sensor, clean it, run it. it'll run like new.

https://www.clublexus.com/forums/es3...e-request.html

look at the first document, the part you should spray some into is that little L shaped hole at the bottom of the throttle body

Thanks for the help i found a walkthrough for this and it helped alot

https://www.clublexus.com/forums/rx-...-write-up.html

It worked! I followed the walkthrough and my idle is better than ever and the car turns over real smooth everytime
So if anyone has a rough idle problem and sluggish engine start its most likely your IAC Valve has carbon build up

I also had a very low idle on my 2002 Lexus ES300 I thought it was the IAC valve or throttle body but all I did was follow this video and got the car to relearn idle and not stall or idle low. 10 minute procedure - cost nothing.