Are you able to see fuel pressure while on track? Many times the stock pump will hold 50 at idle and drop to less than 30 on track at full speed. Check the filter sock on the stock pump to see if it has collapsed in the tank, very common. Do you run an aftermarket filter or stock Mazda. We have the best luck with fresh stock unit. S4 is always lean on top, and S5 is always rich. Do not overlook the AFM sticking. Since it does it with both primary and secondary it is most likely not injectors. Should pull hard to 8400+.
If the motor is in good shape and you are dropping pressure the front cover O ring and the bypass are the most common causes as mentioned earlier. How light did you go on oil? Most run 20/50. Oil cooler restriction is very common as well and can be checked by removal and cleaning. Ultrasonic is only trusted method. Drop me a pm with your number and I can give you some specific ways to fix the mixture.
Steve Eckerich
ITS 18 Speedsource RX7
ITR RX8 (under construction)
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