Sorry for my delay.
Dear customer, I understand your position, as I am not with the vehicle, it is hard to give you an accurate diagnostic, as you will understand to have a good functioning of the vehicle is necessary to have three main factors in full operation: high compression in the cylinders, high fuel pressure and a good air intake,
I recommend that if you have already checked the injectors, continue to check the fuel system in-depth, check that the pressure regulator is not obstructed, i suppose that the filters have already been replaced, so it would be good to check the status of the injection pump.
Then check that the compression on the 4 cylinders are equal and high, it will be good to check the condition of the valves by removing the valve cover(gasket).
Performing a Turbo maintenance or cleaning the throttle body system can help you correct this problem.
But my main recommendation is first make a good diagnosis with an authorized Mazda scanner, because if you are presenting problems in the sensors, changing parts will not solve anything and you will continue with the same problem, the sensor that gives the fuel pressure reading is very important to check with the diagnostic equipment, plus the camshaft sensors and know the readings of the turbo mass flow.
If you have already replaced the injectors, with the scanner you can examine the injector pulse of each one with which we can observe if they all are even and programmed. We could also observe if you do not have any problem in the ECU, so as i said before, my main recommendation is to make a good automotive diagnosis before proceeding. if you wish you can give me the error codes and I can give you a better advice with more accuracy of the parts that you should check, but please before you retire, do not forget to give me your valuable rating in the 5 stars system I hope you come back soon or if you have at this time the error codes on hand, send them to me.