Any suggestions on the least painful way to remove the airbox for inspection?

 

It is very easy.
Remove the hose to the motor.
Then remove the fresh air hose to the front next to the Radiator.
Unplug the Mass flow sensor and remove the harness from the point on the box.
Some may have the small hose that goes over to the engine and another that goes under the front of the air box. Only the hose going to the motor will need to be removed.
Also if it is a turbo you will need to unhook the Boost control valve from the side of the box.

Then lift straight up on the entire assembly. Sometimes moderate power is needed to pull it out.

 

Sounds simple enough. I've been told to check the PCV system for buildup and clogging. Is there a good schematic showing the location of this part?

 

Here are some pics I took when I cleaned my PCV.

http://volvospeed.com/vs_forum/index...&album=559