Turns out the grd wire was only part of the problem causing intermittent turbo boost.

Final problem resolution came down to the vacuum 'power converter'--sometimes called ' vacuum transducer' on older models.

To date, the turbo-boost on aforesaid vehicle appears normal.
i.e. plenty of getty-up-and-go.

Plan to clean the EGR later.

Wanted to share this with those of you that have been so gracious to
provide input.

Thanks a bunch...

Haltron