It really doesn't matter if it stays open a TINY bit while at rest as any air coming through has been metered. As far as I know, the computer simply adjusts it as needed until the airflow is within spec, it does not have a "closed" position to which it returns to when the car is turned off that I've ever noticed. The GTE has a diaphragm following the ISCV which should not allow air to flow back into the ISCV from the intake plenum... The inclusion of this alone leads me to believe that Toyota knew it was going to be open to some degree in all situations.
__________________
If something breaks or you need to contact a member of the administration please post HERE. Unless it's a private or administration matter please post it on the forum. It benefits no one else if car related questions aren't posted for future users and takes away from the time I'm able to spend helping on the rest of the forum.
If you're so inclined I'm always more than happy to accept tips via PayPal. 
Tip Jar ---> 
|