As I wrote, this behaviour does not
have anything in common with the throttle, cable or routing!
The spring pulls the wire always back to the initial position. It hits the suspension point of the disc, where the bowden cable is attached to.
Also there is nothing wrong with the idle screw. The idle rpm is great, so is the rpm when cold.
You can let it run on 1150rpm until it reaches 80°. Does not matter if neutral or pulled clutch.
If you now raise the rpm, f.e. to 5000, it will stay on 4000 after releasing the throttle.
It seems that it is temperature depended and the rpm will stay higher on higher temperature.
The only way to lower the rpm, is to clutch in with breaks on, careful.
Same thing happens while driving. You will feel, that the engine break is missing. Pulling the clutch lets the rpm stay where it was.
My uneducated guess is, that one of the sensors (TPS, S-TPS, IATS, IAPS, whatever
) has a cold soldering or the resistor is done.
I´ll try to check your suggestion
and disconnect the sensor to see what happens