Going to keep it short. For a couple of months now ive been getting these on and off CEL lights and misfire codes at 2nd and 3rd gear above 6.5k rpms. Got new NGK sparkplugs wires and coils, put them in late december. I also cleaned MAF sensor. New after market cat was put in the same day as the new coils plugs and wires. I do feel just a little loss of power and over the months the cold start of my car has increased by around a second or half a second. I got a compression test first day i got the car, numbers were not that low but on the low side. P0171 saying bank 1 too lean. Every time it comes up i go check it at orileys or somewhere else and its always bank 1 too lean. I put in those stp or gummount fuel injector cleaners when i refuel, using premium, and it helps i guess for a few days and later comes back. Any ideas??? Have took it to mazda dealership but they cant do anything bc the codes go away randomly and come back randomly. I went 2 weeks without the code and it popped back up today. 2004 AT 78k miles. Located in VA.

 

BOTH BANKS ON LOW SIDE BUT WITHIN SPECIFICATION. BANK 2 LOWER THAN BANK 1. 814 745 737 KPA, 107 97 96 at 243 rpm, 683 721 691 KPA, 90 95 91 PSI AT 247 RPM.

^ late nov 2021