I just wanted to share the results I've had with the inline filters I installed in the engine bay vacuum lines. The vacuum setup is entirely stock except with the insertion of the two filters right at the main vacuum line nipples.
The first filter is for the 3/2 valves, part of the transmission, EGR, etc. and it has shown some soot in the lines.
The second filter is for the ACC, door locks, etc. This one is still quite clean, actually.
The filters have been installed for roughly a week. They're originally fuel filters, I found out, but the paper filter inside them looks like it can also filter out the soot. Hopefully I won't see any oil in there in the future...
looks like I'll see if I can plug one or more of the lines and see which ones are iintroducing soot into the system. Is the vacuum line going to the EGR valve directly linked to the whole vacuum system? There's a switch valve on the thermostat housing where the vacuum line from the EGR goes to, and then out towards the 3/2 valves black box, and then to the Y fittings and the filter. I'm curious if there really is a direct link. Hmm...