OK, I now have sudden idle improvement syndrome...
Heres what happened this time: Car sits in parking lot all day. I go out, start the car up, experiencing about the same problems. As I am warming the motor up preparing to GTFO the revs fly up to the rev-limit... the accelerator got tangled up in the floor mat (bye bye floor mat). I kill the motor, no harm done. Start up again, problem gone.
I am thinking that Jim may have hit the right answer, a piece of crud (maybe broken off varnish) in the idle mixture circuitry. If it was a bad load of fuel, I doubt gunning the motor would have made a difference.
I am going to run a batch of SeaFoam through the fuel system to take care of any residual crud. At the end of the season, I'll do the Crankcase and the Intake manifold as well, change the
oil, and put some Lucas stabilizer in the fuel tank.
Thanks again everybody, informative as always.