Feel free to use as a techinfo article. Source: http://lesabret.com/phpBB/viewtopic.php?f=13&t=6107
Introduction:
The PCV Valve (Positive Crankcase Ventilation) allows for proper air pressure. You build up a lot of pressure in the engine and If you didn't have the PCV, you'd blow gaskets all the time.
The most common cause of failure is carbon deposits fouling up the openings of the valve. It is possible to just clean it out with carb cleaner, but if you have to remove it you might as well replace it since it is so cheap.
To test just how far gone the old valve is, just shake it and hear how much it rattles. Now shake the new one and compare. The new one should very easily rattle and the old one may make a more dull thud-thud-thud than a rattle.
Autozone Part No: PCV 1209, PCV 129 (about $4)
Removal:
Valve Location: Pulley side of motor, in the upper intake manifold, near power steering pump, under bundle of wires.
Note: The rubber grommet that the PCV sits in and the hose leading to it may be dry-rotted due to age. If so, it is recommended to replace the rubbers with new pieces that can be had from a dealer or Rock Auto for a reasonable price.
The easiest I've found to replace one is to use a large pair of pliers to take the clip off, and then use a screwdriver wedged against the fuel rail (as leverage) and pop the valve out that way.
Installation:
I use the same screw driver and a hammer to lightly tap the valve in tight (after replacing the hose otherwise its very difficult to move the hose in the right position after the valve is in place).