Very high idle

A bit ago the dog and I went on a fairly long trip. Had cruise set at an average speed of about 120. Every couple of hours we would stop for a break and when I put the truck in park it would idle at around 2000 rpm. At first I thought maybe throttle sticking but no matter how much I fiddled it would not come down. I also thought cruise control was staying on so on one of the legs I turned the cruise off before touching the brake to slow down. Still no change. Anyone encounter this before or have any idea. It only seems to happen on long trips over 3 hours or so, and randomly at that. Oh ya, I am in Canada so the speed is in Kilometers per hour not mph.

Vacuum leak or bad Idle Air Control valve (IAC)

Likely the IAC since it's random. probably just sticking when hot enough. Can just be cleaned up with carb cleaner.

Red arrow is the IAC

Thanks FR-425. Appreciate the quick response. I will give that at try and see how it goes. May be a bit till we take another long road trip so that I can test it.

A quick troubleshoot is when it is idling high, tap the IAC with a screwdriver or something and see if the idle comes down. I would agree with FR-425, however.

I just had this; shop clanged out a stuck idle control valve.
All good now.