Car is either an '01 or '02 Passat (not mine), had the P0171 code thrown by the engine. Quick look under the hood yielded this:
When the engine is running, this vaccum line flattens like a pancake, and as you can see, the vaccum is so great it has literally ripped the line open (inbetween the red lines). So something is clogged big time. My guess is that the intake manifold pulls the air and that something near that Y-connector is clogged up, thus the manifold vaccum has destroyed that line. So where is the likely culprit? And what could possibly clogged such a large diameter pipe? I think oil blow-by is unlikely to cause this sort of clogging. Thanks for any input!