I installed a 65mm ford racing throttle body. When I take it for a ride and watch the stock a/f meter it seems to be back and forth. When I punch it I get 11.8 to 12.8 and if I come off the gas pedal it seems to shoot up to 16 to 19. Looks ok with normal driving running 13.8 to 14.5. Along with the 65mm tb I have a air raid filter, frpp resonator delete and corsa axel back. Stock tune. Is the stock a/f meter accurate? Do I need a flash tuner? Thoughts?