what would cause my pcv valve to get clogged with oil and crap about once a month it makes my engine stutter untill i spray it out with carb cleaner

 

Unfortunately the PCV sits onto the valve cover which has tons of oil going everywhere. And the PCV has a vacuum which can suck up oil. But it is not to be working all the time. If your PCV is dead it can stick open and run all the time which will cause it to suck up oil constantly.

I would say replace the PCV as well as the Breather filter. They work together.

 

blowback from the cylinders is a big cause. are you burning a lot of engine oil? the engine could be worn out.

 

im not burning a lot of oil. The engine has 133k on it and i take care of it. I think my plenum gasket is bad but i cant find anywhere that shows how to change it.

 

it's not that bad, i changed a center dome on a 305 two barrel over to a 4 barrel while it was snowing.
remove the lines to the intake. remove the throttlebody and lines. remove the bolts from the center dome to heads ( keep the bolts in order so you can put them back in the exact same holes! )
pull off the center dome and flip it over, theres a plate on the bottom. remove the plate and replace the gasket.
make sure you torque everything back down to specs.

 

Check the FAQ for the service manual. It has detailed instructions and great pictures on the removal of the intake. Then you change the plenum gasket.