[leesrt]

Why are my screws stripping when i try to screw the new one in?

Look at the old one. The old one was cross threaded in when it was installed. Your valve cover may be stripped or cross threaded as a result. If it's just cross threaded you may be able to clear out the cross threading with the same sized thread tap. Your basically slowly screwing in a tap that is the same size and thread count as the valve cover hole. You screw in a few threads and then back it out. Clean off and shavings on the tap and then do it again going a little deeper. Keep repeating till you get it cleared. Don't try to put the PCV with the bad threads back in. You need a PCV with clean threads. I wrap mine with a little Teflon tape as well.

Someone else here may have a better suggestion.