Another place to look:   The digijet auxiliary air regulator.  This
device has a bimetallic strip which when cold lets more air in, and
when warm closes to reduce the air available at idle.   I was having
idle problems on my 85, and found the AAR to be sticky and not open
or close fully.   A malfunctioning AAR will make it hard to set your
idle speed correctly -- the idle adjustment screw will either be too
open at cold idle or too closed at hot idle.   I don't think they go
bad very often, but are often neglected in diagnosis.