1997 Chevy Lumina

I have a 1997 Chevy Lumina. It barely holds anti-freeze at all. If i put anti-freeze in it will run fine for a little while but when I come to a stop or when I let it sit at idle the temp shoots up. When I look under the hood there is a loud hissing sound coming from under the throttle body or the intake manifold. It also looks to be wet in the same place but I can't see where the anti-freeze is coming from exactly. Please help.