I just got a 2.3 2008 manual tran.
I picked it up in Idaho and drove it to Arizona.
It never interfered with driving but every time I let off accelerator and pushed the clutch pedal (to shift) the engine speed slowed down very slowly. approximately 3 times as long to get from shift time to slow enough to go into the next gear.
It does not seem to be symptomatic when parked in neutral.
also checked the pedal, cable, return spring all seems to be functional.
and clutch fully disengages. Any thoughts?

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2008 Ranger (Mazda 2300)

If the IAC is not working smoothly, you can get faster than normal rpms which would do what you describe. There is also emissions control mechanisms that may be slowing down 'throttle closing' as when you 'lift' on upshifting, the emissions may increase. Slowing down the throttle closing reduces emissions produced a 'closed throttle overrun'.
If the 'hard idle' is set too high, the IAC cannot control idle rpm, as the 'hard' idle screw is keeping the throttle plate open a bit. The IAC cannot control idle speed lower than the actual screw setting holding the plate open a bit. It should be set for ~500 rpm with the IAC disconnected. More or less.
tom