No power and poor gas mileage

I have had engine light on and rough car idle for a while now and changed throttle body. It stopped the misfire but would not start now. So I changed crankshaft sensor and now it had a long crank and very little power and high fuel usage.

I have changed the spark plugs, ignition coils, camshaft sensor, o2 sensors and throttle body. Do not know what this could be? My vehicle is a K12 model.