No power and rough idle
 

Hi all! I've been having an issue with my Miata.

Car: 1997 Mazda Miata Base w/AC, no ABS

Issue: down on power, random misfire code, doesnt idle right.

Work done: replaced fuel filter, replaced injectors, replaced spark plugs, replaced crankshaft position sensor, replaced TPS, tested fuel pump and found good, smoke test revealed nothing, messed with ignition timing and found good, tested fuel regulator and found good, tested PCR solenoid and found good, tested MAF sensor and found it to be good.

Stuff to test/replace: IAC valve, compression test, spark plug wires, coil pack.

Any help would be appreciated!!

unique ECU???
 

ok, so... i've narrowed down the issue to my coil, which i replaced with the stock NA coil about a month ago. The coil burnt out, which leads me to believe that my specific car/ECU has an NB ignition chip soldered into the ECU. There are a few reasons i believe this to be the case:

1) prior to the NA coil, the car had an NB coil installed for a few years with no issue, but now it's fighting me when i install an NA coil
2) it's a 97, and was one of the later cars off the production line, meaning they were probably throwing it together with whatever parts they could find
3) the car came from the factory with 15" NB rims, which tells me that the above point is probably the case.

So, i've swapped back to the NB coil seeing as they play nice and haven't really had an issue since. Probably going to order a new NB coil anyways seeing as this one is a tad bit old as it came out of a friends NB, but still runs (has the occasional stumble near idle).