Swap Grounding Gremlins! Tips on SENSOR ground please

The black wire with light blue tracer grounds through PCM at connector 1, pin 4. It goes to some main engine sensors through splices without going through the PDC but also goes to other items like cruise control switch by going through the PDC.
The PDC itself has joint connectors that have some of the ground wires connecting together, basically, and the few actual ground connections go out the square connector, that has 43 pins, out to a couple grounds.