As far as linkages and springs are concerned everything is there as far as i can tell. I only know of springs that connect near the throttle body that keeps the keeps closed when not in use (and it's there), and the other is in the cabin above the pedal. Wiring wise, the rebuilt electronic throttle actuator (ETA) took care of that.

The throttle actuator was supposed to have come set up and ready to go but should I have the car's computer "re-learn" the ETA at a shop with their programming equipment?

I got the impression the computer assessed the ETA every time the key was switched to the run position (the little half second "boot" for the car's systems).

Is there any way the transmission might play a role in the way the car idles?
When I roll up to a stoplight/sign I occasionally put the car in neutral and coast to a stop. When I do this the car's idle jumps to where its happy at 1600 RPM, but the instant the wheels stop turning the idle will drop to about 1000 for quarter second then pick back up to 1600 RPM.

Again, it's a weird problem and I'm pulling my hair out trying to fix it.
Thanks for any suggestions