yeah the brake booster was on the main tree - no joy on it being there. running out of places to look!

I'm going to run another smoke test tomorrow on the engine only portion. Even if there are small vacuum leaks like in the throttle body, I want to find the one that's causing these problems.

Manifold to head connection - meaning where the lower manifold attaches to the block / cylinder heads?

 

So i've essentially ruled out vacuum leaks entirely. I ran another smoke test, this time with the EGR closed off, and MAN did that thing hold pressure. No smoke visible out of anywhere!

So I'm back to square one... no idea where to go with this. Any suggestions?