UPDATE.....I now have resolution of the above problem but no diagnosis. Basically, over a two or three year span, all ECM sensors were replaced. The ones that made the most difference in the intermittent engine power "sag" were the cam position sensor and a "new" from Ebay ECM. This ECM came from a running car. The last thing I did was to replace the fourth and last oxygen sensor (downstream). All engine performance disappeared instantly and the CEL has been off since. So nice to have Sapphire running as she should once more.

Bill Livingston