This is the stepper valve that connects from the air box to the intake manifold to give air for idle when the butterfly valve is closed. I think mine is working but maybe just not well? Once the bike is warmed up it's fine, but maybe it's sluggish due to debris or carbon as a cold engine take more adjustment with the IAC I hear. I've cleaned it with throttle body cleaner (best I can as you can't open it up).
Anyways, just curious if anyone else has had theirs go bad. I'd assume it's probably the same or close to it in the vespa 150s. Old owner used crappy gas with no stabilizer, so might explain why other don't see it as they actually care for their scooters.
It looks like the picture below.
