Oil Galley Plug (the one rear of intake)

You sure oil from the lower intake manifold isn’t just leaking and pooling into there?

That boss is actually where the knock sensor goes on the f150 application. Not used on the Mustang and it’s a blind threaded boss. You must have an F1SE block from a 91-95 Mustang or Explorer.

That’s why I ask if the lower is leaking because that just goes into iron with nothing around it. The actual oil plugged port is under the manifold so any leak goes into the lifter valley anyway.