With the onset of colder weather here in WY, my van has taken on a new
ailment.  When I first start the engine and the engine is cold, it will
idle at about 400 RPMs and a high pitch screech will sound from the
engine compartment.  If I rev the engine, it stops, and it stops if I
run the engine for 30-40 seconds.  The noise has been getting
progressively louder as the temperature gets colder.  I haven't been
able to get to the engine, before the screeching stops, so I can't
identify where it is coming from.  Is the low idle related to the
screech or is the screech related to the low idle?

Any ideas what this problem could be?

Thanks,

Stephen Jones
'87 Westy