I actually reached out to my father to ask about this because the machanic was a buddy of his so I thought he might have some info. It was indeed a vac system issue.

I also live in a heavily salted area, so yeah. Rust did the body in before the engine went out. When you finally retire yours, make sure to pop the “Turbo Diesel” decal from the back of it. I still have mine sitting on a desk at my parents house. A nice memento of my many good years in that car.