Dug into the wiring today. Found some of the pins in that connector a little cruddy, but tested continuity through the female side back to the various connectors (IAC, Coil) and the Male side back to the PCM. Despite stressing the wires could not find an open/short in any of them.
Re-seated connector 178 well (not easy, hard to get seated).
Removed the two bypass wires I added and drove the car for an hour. Repeated tests/stresses, still works fine.
Had a momentary instance of misfire on plug 6, but the wires look sort of old and tired so I was thinking of replacing them. I can't reproduce that misfire.
I'm wondering do to the inconsistent nature of the problem, and the fact that I've now troubleshot both the coil (replacement) and the wiring, plus it was also in the IAC circuit, if I need to worry about the PCM?
The goal here is a reliable car, and my wife drives it an hour away from home 2-3 times a week.
Thanks all,
Scott
