check the breather hose that returns to the block isnt "blocked" lol cant see it going through metering head tho could be possible tho although never heard of it happening, wldnt rule it out. take boost hose off turbo and metering unit and you'll be able to tell where the oils comming from i'd immagine!!

as for engine not stalling when cap's pulled off, well could be due to worn piston rings, if ure worried get a compression check, not every RST does it tho afaik, although they should