I bought a new PCV the other week, £30, the one I took off was revision 'F' the new one was 'N' so looks like there has been issues with them. I also bought a new MAF which I didnt need as my old one was fine, that was £108.
Good luck with finding your fault. There was nothing wrong with the PCV, you can have it to try if you want, Its only sitting in my shed.