If I take an IAC off to clean it, what position should the valve be in? Open or closed? How can I tell if it is sticking open?

 

Your truck will have problems maintaining idle speed if its stuck open/closed. Do not try to adjust the plunger on the IAC manually (with your fingers), you will break the IAC if you do that.

 

take it out, carefully clean everything, put it back in, disconnect the battery for a few minutes, start the truck, and let it re-learn the idle.

When the PCM is reset, it 'forgets' where the IAC was, so, it will run it all the way in, to get a new zero reference for it. Just give it a few to relearn idle. No worries.