DAMN I'M GOOD! I think I fixed my car.
I started the car and measured 2.99 volts on the pressure sensor wire at the gas tank sending unit. But as I wiggled the connector, the voltage shot to 5.00, indicating my ground was going away OR the sensor was bad.
Taking the connector off, I saw it - terrible corrosion on the plug. I cleaned the plug and pins with alcohol and let the whole thing dry. NOW when I wiggle the connector, the 2.99 volts is steady as a rock.
I suspect that, after several "good trips", the light will go out and stay out.
BAD NEWS: Water causes corrosion. The only way water got in there was me. I've not been as careful when washing the car with the top down as I thought.