running lean, bad mpg and low power on 2002 Chevrolet Camaro

Running a little lean with bad mpg and low power. Tried another mass air sensor, tps sensor, fuel filter, checked fuel pressure and for vacuum leaks. Long trims showing +6 to +8 part throttle and wot, but at times they can go as high as +16 to +20. Idle there usually fine at - 1.6. They used to read - part throttle and 0 at wot as they should. At a lost here almost.

by in Garden Grove, CA on April 07, 2010
1 answer 1 comment
ANSWER by on April 07, 2010
You would think bad fuel mileage would show up on Long term fuel trim figures, I have seen a lot of cars at zero or +/- 1%. Lexus loss power if air flow meter goes bad and fuel consumption increases. I hate replacing parts without proving they are bad, I would want to see Air Flow meter voltage or grams of air flow readings on a scan tool with a known good air flow meter and I would then look at O2 Sensor readings and coolant temperature sensor reading to see ECU is reading good figures.
COMMENT by on April 07, 2010
I've driven with the maf unplugged a few times and no difference in fuel trims.