Unknown hole

Ok... I've got a 87 Cherokee Chief. Been having over heating problems so I purged the system the other day... after I did so I started to hear a loud whistle and wasn't sure where it was coming from... then I found it..



This is the engine bay from Go-Jeep's page. I don't have a pic of mine yet... but right there where the red circle is it's flat on mine and there are two holes about the size of a pencil eraser. I put my finger over the top hole, nothing happens. Put my finger over the bottom hole... the car dies...I have no clue what that hole is and if there is supposed to be something there? This is the first time i've ever had this problem of whistling... it's right beneath where the tube from the air filter goes into the area where the red circle is... any idea of what this might be? I'll try to get the actual pic asap...

One hole is plugged the other is for the vacuum tube to the MAP. Mine has a double (oval) stopper that fits into both holes at once, half open for the MAP vacuum line and the other half a blind plug. If your MAP vacuum is unplugged, in my experience you have a really poor idle and a really rich running motor.

That was it thanks. I must have knocked it loose when I was releasing the coolant sensor to purge the system. That takes care of that problem... now to deal with the rest of them...