I've had similar idle issues for a long long time. I have a 74mm throttle body with needswings intake and eurocharged tune.
When coasting to a stop and I shift into neutral my idle shoots up to 1500rpm until I come to a dead stop then the idle goes down to normal.
I have two engine codes
P0422
P0432

If I disconnect my battery the car will run normal for part of the day if I'm lucky.

I've already replaced the O-Ring for the throttle body, replaced all vacuum lines and all connections to the vacuum lines have ring clamps as well.
I switched back to my stock tuning and still had the same problem.
Any suggestions?