m62tub44 smoking at startup

i'm driving a bmw m62tub44 (4.4 v8) equipped range rover which on startup smokes for a few (about 5) seconds or so. the smoking does not occur every time when one starts her and the amount of smoke also differs from time to time (sometimes a lot sometimes a little and sometimes no smoke.

The car does not smoke whilst driving it at all speeds (town and open road).

car still pulls very well in all gears. what we've done thus far is to replace the PCV in Dec 2013, replace tappet cover gaskets and PCV hoses in Nov 2012.

btw it also sounds if the vanos rattle has started

please advise what else we should look at

thanks