Thanks so much M.B.Doc. It was only partially contacting the metal plunger about half way. I bent it back up to fully depress the plunger and drove it.

It now seems to shift at the correct time. Amazing that something that small could make such a big difference. I also noticed that if the throttle linkage is pushed to full open (while engine was stopped) that the metal pin could hold the throttle open. That would be very bad if you stomped on the gas and it stuck to full open while driving! Is it possible to remove the whole plastic thing with the pin and everything on top of the valve cover? It seems it would be much simpler and safer.

I also noticed that the pulsating vibration that I've felt while driving mostly between 45 and 55 mph seemed to be much more pronounced. I think it has something to do with the tranny not the engine. Maybe it too has to do with vacuum?

Thanks again for your help.