I've seen a similar issue on a different make. Idle up and down was a vacuum leak. Check the intake hoses for cracks past the MAF.

I put a new throttle body on for a while...my thought is that threw off the settings.

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What codes popped up? Is it smoking? Like unburned fuel?

No never any smoke...can't find my scanner.
Got a feeling the plugs may have backed out!
Never experienced that before, we'll see.

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- Clean the ICV.
- Rubber elbow hose is usually cracked by now. The crack is usually on the other side away from you and can only be seen when the hose is out of the car

He installed a new ivc...no change.
I gave him my spare elbow
(I've got the same car)...no change!
We both are discussed with this car but determined to get it back functioning properly.

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Were you able to hook it up to the Foxwell?

Searching

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At 4:22 I think is the answer... Valve Cover Gasket!

https://youtu.be/v-rG9UYYbrA?si=ajl0BmcHCJ0KFB_f

This guy is good.
As for me I did mine a bit before COVID...think I was in denial.
The valve cover can be the air leak itself. We'll see this weekend [emoji50]*[emoji100]

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Mine has been running weird, frequent fuel trim codes, sometimes just dies at idle in neutral (it's a manual) with no code thrown (but restarts right after).

I was going to take out the ICV/IAC whatever and clean it today, but seeing this meant I just ordered a new elbow hose/grommet from FCP... it's almost certainly cracked or will become so attempting to remove the ICV. Prior owner replaced a lot of parts, but not that nor the ICV itself, so it'll wait until I get the new elbow.