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.
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COMMENT by on April 07, 2010
I've driven with the maf unplugged a few times and no difference in fuel trims.