1996 Mazda 323 Help no one can fix

To start with, you need a good paper trail of what has been checked. Each mechanic should have proceeded through a troubleshooting flow chart. They should have written on your repair order fuel pressure results, vacuum readings at idle and at speed, o2 sensor readings, EGR valve operation and a host of other information. I suspect you are not going to the right shop. This car is not OBDII equipped, meaning many of these tests cannot be read through a scanner--they must be individually tested using the right equipment. If there is an independent Mazda specialty shop in your area, that would be your best bet. Good luck