okay i've looked but it seems as if mine is a little different. Okay i have a97 hb with a gsr swap and i am running a JDM itr ecu. I forgot when this problem started but its annoying.. so start and warm up is all normal. BUT when i am driving and as i'm rolling to a light and i throw it into neutral the idle jumps up to 2500-3000 and stays there until i get to a complete stop and then goes down to normal idle 900-850...any ideas? i've checked all my vacuum lines and they don't seem to be leaks at all. It never happened when i got the swap done so i would say it started about month or two ago...or maybe there is a leak that i don't know. thanks in advance

 

Check for intake air leak from the TB and IM gaskets.

Clean the IACV and FITV.

Bleed the cooling system.

 

What's the TB AND IM gaskets?

 

My oh my.

TB=throttle body
IM=intake manifold

These areas are known to leak when not installed properly. Get a bottle of carb cleaner and spray those areas. Look for your idle to jump. Bleed the coolant system, take the carb cleaner and clean the iacv and report back. Your car is obd2, I assume you don't have fitv.