After more research I have learned that this is part of the pulse air system. About the only thing not stock on the jeep is there is no cat converter. At some point a small pipe was welded to the exhaust. I assume this was part of the the cat system at some point. Does the pulse air system actually do its job missing the converter? This particular port connects to a hose that leads to the exhaust manifold that is connected to the intake. Any ideas on this? Plug it, leave it alone or??
I have been trying to get this thing running like a new jeep with all the factory components. Now I am asking myself, What were the AMC engineers thinking with their vacuum design??