Gen2 throttle body sync

[Camel]

Beau, do you have a Gen 2 (looks like a Gen 2 arse in the image, but there's so many Gen 1s fitted with Gen 2 arses these days because they look so beautiful).
If you do, you'll need to disable the idle speed control using appropriate software otherwise you'll end up chasing your tail. As for your question, forget a set vacuum reading, what you're aiming for is for all four levels to be the same.