Help me !!!!! car smokking

[gcharala]

I have a 2001 x5 4.4 v8. For the last couple of months the car will start smoking A LOT for 2-3 minutes and then it goes away, last couple of times, i got a code, misfire on multiple cylinders.
I have change the OS and the 3 hoses about a month ago but the problem is still there.
I have check the intake manifold and there is oil in the manifold. Last week i figured the oil return valve on the rear cover of the manifold maybe blocked so i disconected the bottom end and sprayed carb cleaner from the top and it seemed to be totally fine. is there any other kind of valve on the rear cover that could cause oil to go in the manifold?. most of the time before the smoke there is a hissing noise as well.

Another issue maybe unrelated, occasionally i hear a noise as if a pulley bearing are going bad. the water pump is brand new, alternator works fine, a/c compressor works fine(the noise continues even if i turn it off)
I do not know what the cause or if the two issues are related

I do not believe its the head gasket because the car would not just come for 2 minutes and then go
I have also notice that the car is not as sharp as it used on acceleration especially above 3k rpm
Please help. is there a diaphragm on the rear intake manifold that can go bad and cause oil in manifold???