So today I noticed while pulling into my garage that I am getting an odd ringing noise coming from my engine compartment. It only happens when i rev it up on it's return to idle around 2K. I dont have another person around to rev it up so I can take a closer look so I was just wondering if you guys have any ideas?

 

Rev it up by pushing on the throttle body...

 

^^^
What he means is work the throttle at the throttle body. I have this picture in my mind..............