Hi x-type_lpg,

If you are still tuned into this thread can you please elaborate on the "air flap valves" you referred to on your post #20 of this thread ?
Were you referring to the throttle body butterfly interacting with the idle air valve?
Or were you referring to the single IMT valve the 2.1 manifold has?

I get a sense of slight engine hunting on low RPM during deceleration on mine, which seems to resolve I suspect when the idle air valve is stabilizing its position.
But I recall another recent thread of another member trying to identify an induction fluttering sound after releasing throttle (high intake vacuum) and engine RPM decay.

 

IAC vanve on top of throttle body is stuffed. I had the same thing. Cleaned valve halved the problem. Got new valve