Odd cut out/stuttering issue at specific RPM
 

car: 1993 chassis with MSM engine (8.6 pistons) and no turbo installed yet. AEM EMS V1, NB cam/crank w/ 12+1 wheel, AEM MAP, GM IAT, NB1 mani (VICS wired in), NB TPS w/ VTPS, stock injectors w/ m-tuned dual feed rail, DW300 and fuellab fpr.

I tried to get a base map on my car at some local tuners. Spent a few grand and each time I got back a car that didn't run so I've been doing this on my own. Grabbed another ecu off someone here with a similar set up and managed to get the car running fairly well.

Only issue is that around 5k rpm the car sputters/box and stops. According to the wide band its not going too lean. Plus gap is stock, Tried other coils/wires/cam/crank sensor, re-gapping the crank sensor and the timing map seems comparable to another miata we have with a VVT swap.

Car pulls great up until then but it just feels like its hitting a rev limiter. Any ideas would be apreciated

Pulled some timing and added a little fuel at the top end. Weirdly now it does the same thing at 4K rpm. If I lightly accelerate I can get past 4K and from 5-7 its just fine. What the....