Sticking throttle pedal`s which cause 95%,err well actually upto now 100% of this problem for me do not
generate a fault code
The only way to see fault,which is usually intermittant would be watching live data using datalogger to monitor the 3 potentiometers contained within the pedal.
I`ve never had to do this,when the fault is on,lift pedal.
If idle drops to normal there is your answer.......
Combine that with the fact i`ve never seen high idle for any other reason,pedal sensor everytime.
If your not convinced " borrow" a pedal of something else to try it