Hello, 1990 Miata with MKTurbo kit and MSPNP3. Idle jumps up and down when nearing operating, about 900-600-900, sometimes 1000-800-1000, depending on if I hit the accelerator or not, sometimes it'll stay steady for a bit then start jumping again. I've tried TB cleaning, IACV/ISCV cleaning and electrical test, checking plugs and wires for oil/water and made sure there wasn't a misfire. Checked for vacuum leaks the best I could with limited resources (ie WD-40), and replaced coolant sensors and thermostat. I did not tune it, but it has been running well on the tune I had before I moved to San Diego. I make my own 93 from 91 and 100 and it ran fine for months, then I let it sit for a month or so, then it started acting funny after a highway drive. Tried reading a bunch, couldn't find much I haven't tried yet. Did all the fluids and filters a little bit ago, but as I did not tune it, I can't see 100% what it's doing, but my tuner in Virginia had worked with a ton of Miatas and knew what he was doing. Any info or direction to point me in would be great, thanks.

 

Take a log of it idling weird and attach it here with a copy of the tune too. Otherwise we’re all guessing.