knight akkord

Hey guys, my engine is starting to idle up n down up n down..it reaches 2500 rpm and drops to 800 rpm...and it won't stop. I hear a hisssssing noise somewhere from the intake manifold but i'm not sure if it's related. anyone know what this could be? Thanks.

metpage

sounds like a vacuum line is loose, check to see if all the lines around that area are secured