ok you might need to clean your idle air controler (iac)
because oil thats escapes the pvc valves and oil breather lines will re-enter the engine via the throttle body (tb) thus the iac gets gunkt up with crappy oil and then dosent work properly and you end up with a real crap idle.(this prob always happens on high k engine with worn rings and such which expiriances oil blow by.
i'll give a quick run down on what you need to do
here it goes (feel free to add or criticise this)-
1. unbolt the iac with a 10mm socket (for those who are wondering
is it is the little cylinder shaped thing bolted to the throttle body)
and disconect the wiring conection from the main injection loom and iac.
2. take the iac out and put it on the work bench.
3. undo the grub screws on the body of the iac and then pull it apart (so you have 2 parts)
4.get some mineral turpintine and put it in the iac body hold all the holes in the iac closed and shake it round (use a lint free rag if ur really keen)
5. you will notice a little plunger on 1 half of the iac (the side that bolts to the tb) seal of all the holes on the iac body and fill it up with turps and then press the plunger in and let it come back out on its own (repeat this step 5-10 or so times-so you are sure its clean)
6. leave it all apart to air dry for about an hour or so (if you cant wait that long then use a rag but make sure it is lint free cos any foreign mater in the iac upsets them)
7. while it is drying out take another lint free rag and some turps and have a look at the throttle body and you will notice two holes on the top of it get a thin screw driver and put the rag over the end and drown it in turps then push it back and forth in the holes on top of the throttle body.
8.check the iac gasket is not cracked or torn if so replace it with a new one or cut another one out of hard paper or similar.
9. put the iac back together then reinstall back into the car but make sure you put the gasket and iac in the right way.
10. disconect the battery for 10 min to reset the ecu then start up the car and observe the idle.
11. if the idle still has probs-well then i've just wasted my time doing this post and it is obviously something else!!
i did this very often (every 3 months)with my ea cos it had idle probs and it was a 230 tho engine and was always reing reved to redline and back (i wanted to kill the engine).and every time i did this my idle probs went away
sorry if this post is long and jack feel free to move this post