GM-GMC: fast idle 1992 chevy 1/2ton 350 truck, vacuum leaks, air control valve

Question
My half-ton 1992 350engine chevy truck idles now at
1350 rpm when warm.  There are no codes to retrieve.(not on the dash or via code-reader)
Otherwise it runs good.

Answer
First thing that comes to mind is a vacuum leak.  Check around your intake for a leak of some sort, that would cause a fast idle.  Or if you have no vacuum leaks, try removing your idle air control valve and clean it off (very carefully).
Hope this helps.