I got rid of my daily beater and started driving the Z again, and just this past weekend it was acting strange for a few minutes. I noticed a sputtering or misfire type feeling... I was in traffic, so I only got the car up to about 2.5k RPM before I found a gas station. It seemed to idle fine in the gas station, but if I gently blipped the throttle it would pop/backfire and it just seemed a rough. A few mins later the "sensation" went away... and hasn't come back 200 miles later.

I had the car tuned a bit a few weeks ago... compression checks, scoped the cylinders, changed the spark plugs... etc...

Any ideas what this could be? Spark plug bad... arching with the coil? Something to be worried about?

 

FOLLOW UP

Turns out my HKS Twin Power DLI II has a problem (or the wiring harness). Disconnected the piggyback connectors from the coil, put on the OE and the car runs fine.