All the guides I found seemed to imply removing the nut from the bung on the intake manifold would be trivial. It was not...

It also wasn't clear that the pipe and nut should move independently from each other.

Here is a video of how I was able to remove mine.

Tip: lots of PB blaster or Liquid Wrench and patience.

https://youtu.be/KLgyTKTiyWw