Tough one to solve. Since it seems like you've tried everything else, I'm still hung up on a possible problem with the circuitry itself.

From the relevant '97 Ford Manual wiring diagram, it looks to me like the two-wire CMP sensor is grounded by way of the wiring harness itself (that's usually what the dotted lines mean). I'm not familiar with those types of CMPs, though. What does the CMP harness connector and the wire harness itself look like? Is it some sort of cable with two wires running through the center wrapped in a metal ground shield?

As you can see from the diagram below, the 2-wire CMP ultimately gets grounded by way of a splice (S107) into the main wiring harness that runs to the ground screw (G102) located up on the fire wall, just to the right of the PCM harness connector.