ok ive got a 05 impreza has 2.5sohc engine ive been losing power lately hills i use to climb in 5th im now barely holding 4th and even sometimes down in 3rd the car is using about a qt. of oil every 150 to 200 miles no signs of leaks ive looked all over the engine and its not blowing smoke have no clue where its going, and its pinging boarder line knocking mainly on the highway with little to no load if i put more load on it it goes away, ive replaced the plugs and have checked them since looks like its running a little on the lean side but not too bad. it will throw a cel for the vapor recovery same code if you have a loose gas cap and cruise light will start flashing but no knock sensor codes or anything like that. if any one has any suggestions or ideas im all ears ive been scratching my head since december on this