the idling problem wouldnt have anything to do with the a/c. if it needed to be charged, then it just wouldnt blow as cold of air. it wouldnt make the car idle up and down. if youre thinking there isnt enough refrigerant in the system to lubricate the components and is actually slowing the engine down, thats a misconception too. if that were the case, he would have no a/c at all because the low pressure sensor wouldnt allow the compressor to cycle.
the cycling compressor clutch is perfectly normal. the compressor is never engaged at all times when the a/c is on. it always cycles on and off.
as for pcv valve, if it was soooooo bad to do something like cause an idle problem, your dipstick would have shotten out of the hole, and there would be oil leaking from every place on the block because of the built up pressure from having such a clogged pcv valve. so you can rule that out too.
there are ALOT of problems that come up like this ALL the time. looks like youre new, but im not going to tell you to search because then i have to provide a link to the topic youre looking for, and i dont feel like searching for one right now. but i can tell you it is vacuum related. check all the vacuum lines to make sure theyre not cracked or disconnected. take a squirt bottle and fill it with water. spray each vacuum line with it, and spray along every seam on the manifold. what will this do? if you spray soemthing and you hear a change in rpm, then that means that the engine sucked up the water you sprayed on there. thats not good. however, it kind of IS a good thing because that is where your problem lies. whatever you spray and the rpms change, thats what needs to be fixed. its amost always nothign major like a cracked plenum or something like that. its usually a bad gasket or vacuum line. if thats not the problem, id suspect the idle air controller, or the fast idle thermo valve. does it only do it when its warm, or does it only do it when the engine is cold, or does it do it no matter what the engine temp? any check engine light?
i hope some of that info helped, post back here and let us know what you came up with.