I'd say that I'm 99% sure that it's not the throttle cable. Visual inspection: watching the throttle body blade, the cable, as my brother sits and actuates the pedal --- everything is snappy.Are you sure the throttle cable is not sticking?
To open up the IAC just use a hacksaw and turn the security screws into flat head screws. I clean mine with solvent, and then oil it, chuck it in a drill using a short rubber tube and give it quick spin. That usually laps it nicely.