Help GSR problems while driving

When I drive around and I hit vtec the cars is ok but shortly after 3 gear vtec/ 4 gear transition it just dies. The engine turns off. I was using a modded LS harness for a GSR so I finally got the actual GSR harness and it didn't do it. I drove it today for work and it died again but turned back on quicker then yesterday. Is it the ECU? Or is it the in driver compartment harness that's bad? Or something else?

Are there any codes?

i cant tell cause im using OBD1 on a jumper cause i had it chipped. i think it could be the ecu cause i connected everything correctly and it started and ran fine. i think the ecu is surging and shutting it off. im running a p06 on it that has been remapped. its been fine till this weekend. could it be the ecu? or something else?

If you suspect the ecu put a P72 ecu in...