December 11, 2017
The fires here in SoCal made it tough for me to work on the Z, but the car is finally FIXED!
Ok so I feel REALLY STUPID, but basically it came down to one or both of the Camshaft Position Sensor connectors coming loose.
I basically found this out while the car was running - I was frustrated and started tugging on wires and plugs when suddenly I felt a tiny "cough" in the idle throttle response. Turned out it was the driver-side CPS plug. So, I cleaned it up and connected it and throttle response came back the next time I started the engine. Ahhhh... 5000+ RPM revs, how've I've missed you.
Hindsight
Looking back, I do recall having replaced the spark plugs recently (~6,000 miles ago maybe). Part of that process involved disconnecting/unplugging various connectors in order to remove the intake manifold and parts. My guess is when I put everything back I didn't double-check my connectors, which that one then later unplugged itself under some harsh driving conditions.
What I don't understand is why I didn't get other codes, like for the Camshaft Position or Idle Air Volume or something else. I just got a vague P0300...Anyways...
Lesson learned - Always make sure you push connectors until you feel/hear a 'click', otherwise they will unplug themselves and cause you a bunch of headaches.
Anyway, I hope my experience helps someone in the future!
