Lindsey narrow band O2 sensor monitor (with injector duty cycle monitor) shows solid LED's (no dithering). Would this happen with an O2 sensor that is going south? Or could it be wired incorrectly?

It does light up different LED's indicating richer/leaner upon acceleration/deceleration/easing up on the throttle, but the lights remain solid.

 

It could be a problem with the O2 sensor, with the DME, or with the wiring between them. Check the 3-prong plug to the sensor that's held in a plastic clip on the middle of the firewall. I've had problems with bad connections in that plug.