www.RX7fb.com

I've got an errant hose coming out of the intake manifold. It starts metal, changes to rubber, and ends in metal, and goes nowhere... what is it?

Think you're indicating an air pipe. From the factory this ran back as a small pipe with a stainless bellows section where yours has been made rubber. From memory this pipe went into the side of the first silencer on the factory exhaust.

When people fit a replacement exhaust the air pump and thermal reactor system are removed This pipe is also taken off. (90% of owners have done this).
Usually it's blanked at the manifold.

I was going to guess coolant-related. But then it should drip. Just make sure it's not a massive vacuum leak, or it'll never run.

I thought coolant at first too but it doesn't leak, so air hose... hmmm I guess I'll just remove it and cap it off. I don't think it's a vacuum leak cuz she runs.