That is the crux of my problem Doc. Thanks for the tip. Driving home tonight in stop and go traffic where acceleration was very gentle, the shifting was smooth and frankly better than before with no lock up thunk. It downshifted properly too. But at the exit ramp when speed up need was more "normal" the slippage between gears as you describe it is really disconcerting as you can't accelerate much for a couple of seconds until lock up completes.
Still looking for additive advice since I continue to wonder if the Gunk product I used is a part of the problem. Its called TransFusion and the bottle says it conditions and loosens sluggish transmissions and mine sure is loose now.