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Q: loss of power. 2003 Mazda 6

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Ok I have a 2003 Mazda 6 2.3L and I just rebuild the engine and after having spun rod bearing. Had the crank truned and posihed. so basicly long story short everything is new and been build right. My problem is that when I started it the car ran prefect and smoother than it had ever been. It ran good for about a week to week and half and had all kinds of power and ran really good and quick for what it was. Then about the 2nd week it has lost power and will not hardly take off. The think its tricky is that after you get it go it will pick up speed and I can get up to over 100mph if I wanted. But it still doesn't have the power it should. I have tryed everything I know to try. Not bragging on myself but I am ase certified and pretty smart on cars and it has me stumped. I have checked compression and its good with 125-130psi. Fuel pressure is 55-65psi. I have put o2 sensors on it. I have tried MAF, Coil, pulgs, Egr. I have pulled the intake back off to check it to make sure I didn't miss

My car has 150000 miles.
My car has a manual transmission.

Hi there, thanks for writing in. You should check to see if the timing belt is off or jumped, or your injectors have some blockage and needs to be cleaned cleaned. Also, make sure you have a clean fuel filter. If you still have low take off power, then see if the vehicle revs in neutral without hesitation, then check for excessive back pressure from the exhaust catalyst.

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