06 mazda3 GT manual idle and engine braking problems?
 

Over the past week I've had very weak engine braking with low idling problems. I cleaned my throttle body twice already to no avail. The rpms also seem to get snagged and fall slowly once it hits 2000 rpms. Seems to idle fine when cold. Engine also seems...quieter?...when warmed up. Also (not sure if I'm hallucinating this) there seems to be a slight whisp noise from the front when accelerating at low rpms. I've tried to look around for vacuum leaks as best I can and can't seem to find anything.


Here is a video I took of reving the engine.

was revving it there done slowly, or as punching it to speed up fast?
I can only hear birds chirping for idle - odd engine noise :)
The idle looks to be at the right location, I think ~700rpm is normal.
Does it accelerate normally?
Mileage?