Yeah, I'm a newb here and this is my first time crying out for help. I've got a 97 A6 quattro with 185k miles and I'm going crazy trying to figure out what this noise under the hood is. I'm modestly mechanically inclined, I've fumbled my way through the engine bay enough to know whats what. My problem is there is an audible ticking noise coming from what I'm fairly sure is the intake manifold. The sound is definitely rpm related, it gets drowned out at higher revs but its really noticeable at idle. From what I can tell its not any of the accessory bits. I know there are valves inside the manifold and I've seen pictures of whats in there, but I don't know if those are the root here.

Some details that might help; just seafoamed the whole thing, fresh full syn and lucas oil stabilizer. Noise is not new, just annoying me enough now to try and fix it. Also, the EGR is shot and is currently disconnected from the vac line (all those are fresh too).

Whats wrong?