The little vacuum port on the throttle body - I believe the orifice is covered by the throttle plate when throttle closed - am I right?

I can't recall for sure. I'm picking up on a project where I rebushed (delrin), turned the throat out a few thous, and made a new plate.

The TB currently on my van has become so worn that it is practically impossible to set the TB switch and have it work consistently.

Thanks

Alistair