My 94' Z28 has an enormously loud idle. I started it up yesterday and it had this very unusual loud noise. Its very hard to describe but its like this tubular noise coming from under the hood and it never went away since yesterday. You guys have any ideas on what it could be??

 

can you narrow down the location a bit? Use a piece of wood and place one end on the vibration and the other on your ear... you'll hear the sound get real loud when you find the rattle.