Hi
EGR throttle flap sticks shut, causing no "fresh air" to be drawn into engine, it sucks air via the cam case breather hose(and oil) hence why it smokes and revs.
Check sticking of flap, control electrovalve also
( un offical -offical fix was ball bearing down vac pipe from electovalve to flap) but make sure flap doesnt stick first!!!!

MARK