Z_WAAAAAZ

Yeah, let us know when/if it happens again. I’m having fun coming up with guesses but think there’s currently insufficient information to make a solid call on this.

Gee Emm

That set is missing the usual culprit in these cases - 'dirty windscreen'.

Kyle_MSM

Any thoughts of it being a sensor heat soaking? I'm not sure which sensor would cause that but since there is the belief it might be heat-related it's worth brainstorming that path. Or a dirty MAF sensor that when intaking hot air is losing accuracy?

Z_WAAAAAZ

Not for this scenario, no. Dirty/malfunctioning MAF sensor will cause a constant running issue. Most commonly, runaway idle will be caused by an unmetered air leak, like a vacuum leak or throttle plate not fully closing. For idle to rise to 2,500, you need a substantial increase in airmass.

For starters, I might manually check if your throttle plate has any notable friction when the car is fully up to temp.