Your electronic throttle makes a lot of noise even at idle, normal. It's probably in your imagination if you cant find any leaks and the noise persists. What probably happened is the whistling at high speed made you very sensitive to those types of noises, now you're listening to your car more and finding more "problems". Then you come online and look up other whistling "problems" and this site has turned you into an automotive hypochondriac.
This site is great for that.