I just replaced the distributor, cap, and rotor after having some issues with hesitation, misfire, and loss of power. I also recently replaced the MAP sensor and IAC valve and both connectors. Now there is a loud vacuum hiss and I cannot identify where it is coming from. All of the vacuum lines have been replaced with vacuum hose. So it's all new. One thing to mention is that I did melt a piece of the EAC solenoid when soldering some wires, but it only is a corner of the plastic housing.

I made a video to better illustrate the problem:

 

Wow that is loud!
use a can or two of carb cleaner to spray around the area to see if you can make the engine stumble when the cleaner gets sucked into the engine through the leak