My 1991 5.0 / 302 does not idle up at all when starting in mornings. It idles about 500 rpm in park, when warm about 650 in park.
My other vehicle idles up around 1000 for a min or so then idles down. I have cleaned the IAC ( hope i used the correct initials ) it looks good as far as i know.

 

Have you pulled the codes?

 

No, I dont get a engine light coming on so with it still give a code?
And if so my local Autozone says their coder does not go back to 1991. Should i be getting an engine light. Truck runs great just doesn't idle up on cold starts.....