Here is the outcome... It was behaving EXACTLY like it had when it had once run out of gas... guage said I had just under a quarter tank, but for fun, I popped the cap and threw in a gallon from my garage... I cranked her and she BRIEFLY surged like she wanted to fire, but went back to the same lifeless crank. Given the encouragement of the small surge, I went back and popped off the gas cap and resumed cranking... fired right up!!! I don't know what that means, but she's run fine all day - just a little spark knock at 2.5k-3k rpm or so.
