Tom
you might try and swap your tach pick up from your lead coil pack to the trailing coil pack.
and see if your tach still works properly.
we have run into this in the past, the engine cranks just fine, rev's fine on jack stands,
just kind of soft under load and won't get up to normal shift points.

won't hurt to try.
hope this helps
joe
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Joe, on trailing coil where should we try pickup? Thanks Tom Weaver