Good Evening,
I'm fighting the same problem.
The ISC (Idle speed control) valve is under the Lexus symbol on the intake manifold. It's a round, black item with several hoses and an electrical connector.
Here's the trick: Three of the hoses are coolant lines.
You have to remove the wire cover, one large hose from the intake snorkel, and then the coolant lines.
The valve itself is a stepping unit. This means you have to apply power to it, then ground two different terminals to move the valve.
I'll be pulling mine off this weekend, to check and clean it up. Hopefully, I won't have to buy a new one.
If you want, I'll let you know.
Good Luck B)
Hi please let me know if it worked for you as Im going to try it on mine also