What size injectors are you running? I’m currently on 350cc Denso Injectors and a DW200 FP. I believe TDR kit came with 350s, yes?

This workaround modifies the MAF voltage signal to fake less air coming in. That should shorten the PW and compensate against the larger injectors.
- tap into the MAF wire going to the ECU,
- add a variable potentiometer 0-25k ohms, and maybe an extra resistor in series if you can’t get it in range.
- ground your new, third wire, adjust the potentiometer at idle to get 14.7.

I used this diagram when on 305s. IIRC, I’m at 16.6k resistance for the 350s now. No CELs,14.7 idle is spot on. a little richer than I want as I move into boost, but no more bad idle or babying throttle on startup. I tapped the wire on the piggyback harness to ensure I remember to add it back in during smog checks.

Here’s a diagram:
https://www.miataturbo.net/g/picture/23989522

Here’s the potentiometer I used:
https://www.ebay.com/itm/B25K-Ohm-Li...-/301657236589

As long as you have some half decent soldering skills, $10 and 2 hours, it’s an easy workaround.