I have not been able to work on the car recently. I did buy a new gas cap before taking the car for a drive yesterday.
Ambient temp was 80F and all was 25 minutes into the drive (car engine fully warmed up).Gas tank a smidgen under half full of 93 octane and no gas smell.

I entered a residential area with speed limits on the streets of 20 and 25 mph.
I stopped at a Stop Sign and then executed a 90 degree left hand turn feathering the gas pedal with rpm 1,500 - 2,000 (so I did not speed). Almost immediately after the car turned the corner with no further gas pedal movement my car became a VIOLENT BUCKING BRONCO! Power On power Off, power On Off and repeat the loop multiple times within 4 seconds with perhaps 1/2 second between ON and OFF repeats, until I backed off the gas pedal and moved to a fortunately open parking space along the road. I was lucky not to be hit by a car which came up behind me. I rested the car for 30 minutes and when I returned and it drove perfectly smooth with no hint of what had just transpired. It was amazing how scary this incident was as it was so violent. Note the rpm did not jump at all, but it was total OFF and then back on re the power in the most violent form imaginable.