OK I have a follow up here:
After performing compression and leakdown tests, checking distributor & plugs, valve lift & duration, (none of which were spectacular by the way)my problem ended up being that the manifold gasket had shifted and was permitting air to leak into the intake. This was causing #'s 5&6 to run to lean and stumble.
I'd like to take credit but it was a Porsche tech I know that located the problem.
I hope this can help some of you down the road.
