Idle Problem Troubleshooting

Idle problems on the 928 can be traced to many sources.   This is my attempt to provide a comprehensive troubleshooting guide based on my own experiences tracking down an intermittent idle problem on my '87 928 S4.   The basics should be applicable to any model year, but the information  (WSM pages, links) are specific to the S4, and for the most part later models.  

Currently a work in progress.

Questions?  You can PM me on Rennlist, "fabric", or,
fabric at gmail dot com