Turned out there was a little hole in the oil return hose that goes from the bottom of the CCV/PCV down to the oil dipstick tube.
I ended up replacing the CCV, intake gaskets and a pile of other parts.
The P0171/P0174 codes cleared & stayed away for a short time but they're back again. I think I'll try the smoke test again. Maybe I'll get lucky and it'll just be a damaged the DISA gasket. I watched a bunch of youtube vids by 50sKid that really helped with taking everything apart. That guy seems to do a really nice job with his videos and explains things very well.

Thanks for everyone's help!