Hi,
Just joined the forum so I could share my "fix" of this problem. Might be of use to someone.
Had the same hunting at idle issue on my V36 with VQ35HR engine after swapping the engine because the original one got overheated.
While changing the engine I made the mistake of cleaning the throttle bodies and tried all the tricks i could find to do a throttle relearn with no luck.
Gave in and took it to a shop and they couldn't sort it. Then took it to my local Nissan dealership and they couldn't get it to idle properly. They said I'd need to replace the throttle bodies and the ecu probably costing more than the car is worth.
So I had the idea of replacing the carbon I cleaned out with a thin layer of super glue and it's back to normal idle now.
Bit rough but saved the car from the wreckers 🤣