Noticed over the last week that my 99 Vette seemed to be missing/stumbling a little on idle and I was looking into it today. Under the hood, it seems to have a loud hissing, whistling or sucking show and it was louder than I had heard before. I located the area on the front passenger side of the engine. I was checking hoses/vacuums and found the below picture where the majoriity of the sound was coming from. It doesn't seem corroded and its either hard rubber or metal but it has about 1/8th inch hole completely through it. Seems to have been made that way and when I pinch it (fingers over both sides of hole), the engine drops to a lower consistent idle and the whistling goes away. Can someone make out from the picture if this 'part' is supposed to be that way or is something missing?. I honestly don't have a clue and the little bit of looking via the net hasn't helped much. Thanks in advance for any and all comments. Tip of my finger is pointing at the 'part'.. (sorry for the size of the pic, didn't resize as i wanted..)