When I start my car when its cold, it hisses like hell. I mean loud enough that if I have the hood open, I can hear it in my house. When it warms up, it goes away. This is on my 92 vert lb9 btw... Im running an open element filter on the TB, but I dont ever remember it being that loud when I had it on there a while ago.

Any ideas?

 

It is your IAC valve. It's like an electonic choke on cold start up.