2000 740il with oil in intake manifold...???

Hello everyone, newbie here and experiencing some difficulty in tracking down my issue...
I initially though it was rear OSV because had smoke at start up, rough idle, oil in intake.....
I removed intake manifold and replaced OSV plus ALL seals and even the vent pipe put it back together. It started right up ran it about 20 miles and on way home SES started blinking and got home and pulled codes p0135,p1174 and 1175 plus the p0301,0302 0304 misfire codes. Opened hood and could hear howling noise coming from intake @ OSV along with suction at dipstick, which didnt have before as well as oil in intake again along with oily fouled up plugs....hence the misfires....... So now i'm really confused....could it be the Cyclone Separator causing all these issues???? Would it cause the howling noise and all the oil being siphoned into intake manifold? Any and all guidance is sincerely appreciated.....