Hi Concrete, Super mechanic here. I just have a couple of questions about your car.
What year, make, model is it?
Are there any service lights on?
Have you checked, (or changed) the fuel filter? Is there a good flow out the exhaust?
Air filter good? You could take the 02 sensor out of the exhaust manifold to see if it will get more power. That is if it seems to have a lot of back pressure in the exhaust.