the head gasket :
if volvo or equivalent oem
it's there
http://www.scribd.com/michaelovitch/...sket-mls-volvo
you don't need a torque wrench for the intake manifold.it's overkill here.
tighten from the center ang one left one right
then check from one side to an other.
if it's loose it will suck of course but you should check your valve first like it was said.
but it seems strange that all your valves are out.
are you sure it's not a residue of some assembly or cleaning product of stuff like that let by the builder ?