I would check the Air Flow Meter per Bentley Manual with a multimeter.  This
is usually the culprit.  Also check the Temp II sender, and the idle switch
under the throttle body per Bentley.  I have new 2.1l AFMs for $120 if you
need one.

Thanks,
Ken Wilford
John 3:16
www.vanagain.com
Phone: (856)-765-1583
Fax: (856)-327-2242