i have a 2006 nissan titan with 94,000 miles and i noticed a whinning sound under the hood on the driver side somewhere on the engine. when i idle up the engine i dont hear it but when it idles back down in park you can hear it whinning like a bad power steering pump but kinda on the quiet side. its not the belt, power steering pump, pully etc. im thinking its the injectors but not sure. any help????????