[CHEVYCRUZE RS]

Change even the downstream O2 sensor, I know its far stretched but you never know! Inspect your evap purge line as well and double check PCV line, make sure it isnt clogged! You can open your intake to where it connects to turbo to see a bit of oil in downpipe, this is normal but you shouldnt see too much oil!

 

[CHEVYCRUZE RS]

what if there a good amount of gas and oil in the down pipe on the manifold where that hose runs from top of intake manifold to the turbo?

How much oil are we talking ? It is normal to see the drainage being shot into downpipe but it should never be a big amount or even gunk up at all id that makes sense if that’s happening then I would replace your PCV system could be faulty