My car has way less power in lower rpms and not much better in high rpms and smells like it is running really rich. The Idle Air Control Valve is making a noise now when i turn the key to on and a weird noise after i turn the car off(you can hear this after the engine actually stops running for a sec). I checked the ecu for codes and it was fine 05 05. Check engine light is off. I always run at least 91 octane, new air filter, new spark plugs, run injector cleaner every 5000 miles or so. What could be wrong. Is it possible it is the knock sensor.

 

Come on someone has to know something