High Idle CIS
 

I'm trying to diagnose a high idle issue on my 81 ROW 3.0 SC. It starts fine, but as it warms the idle creeps up, til it gets to 3000 rpm. Screwing the idle adjustment screw in all the way brings it down to about 2500. If it sits for 20 minutes, the idle comes back down, but after driving again will begin creeping up again. What components should I be looking at here as the culprit? Thanks for any input.

WUR, AAR, AAV, decel valve, distributor, and air leaks for starters.

That sounds like a big enough leak to be a intake runner boot, or a hole in the main inake boot, time to get some ether and start spraying for leaks.

My '80 SC did the same thing. It was the AAR (auxiliary air regulator). Replaced it, and it ran like a champ.

That, and more.
Idle adjustment screw in all the way? That doesn't sound right because it is part of the mixture adjusting process.
Winterfarm: Get a Bentley SC Repair Manual and read, read and learn how the CIS-components work. The AAR would be the first thing to look at with high idle.
You can do a search but why not get a Bentley?
Without knowing the condition of your engine and what maintenance has been done, it's hard to diagnose. :)