Idle Speed Fluctuates

I have a Speed Demon 575 on my 65 and have been trying to get it running correctly for a while. Right now my engine idle speed will either be really low and will die or it will go up to 1500-2000 rpms. I think it is my PCV valve though as this is something I had changed recently. I am also pretty sure it is incorrect as I did not know which one to buy. Is there a way to find out which pcv you need or something? I have a breather on the other side which has smoke coming out of it also. I have tried adjusting al the idle mixture screws and idle speed screws only to have it go to the extremes of dying or idling at 1500-2000 rpms.
Would reallly appreciate any help....Thanks

I did not just buy the car. I have had it for 2 years now. Ran it back and forth from highschool for a year then the engine seized on me because of loss of oil pressure and no oil pressure gauge. Since then have purchased a 66 block 289 got it all running using a lot of parts swapped from other engine. For a year now I have been trying to get it roadworthy. Since I have not had the engine running a lot I am not sure when the problem started and I have messed with a lot of stuff since, but I am pretty sure it is carb settings+pcv+crankase pressure. I had taken it to my shop guy and he said I had too much crankase pressure, and the pressure was forcing oil into the distributor cap as the seal on the distributor is shot. So he said I needed a breather intead of my plug on the valve cover. While at the auto parts store buying a breather I also figured I would replace the pcv as it was the same one I had on my old engine just swapped it over, but me not knowing any better just grabbed a pcv valve off the shelf. I had also played with the carb settings including the idle speed screw :/ , idle mixture, and my idle-eze thing. All I could get was either too high of an idle or it would die. Shop said this was also because the of the oil in the distributror cap. So now I put on a breather and new pcv. Smoke then came out of the breather and I am not sure why? And I still could not get it to idle right, but I still have not changed the distributor seal.

Since all this I have just put the old pcv in and I think there is now less smoke out of the breather and I think it is idling better, however I cannot tune this demon myself so I know for a fact the settings are off. But I am not sure if I solved anything yet because what do ye know I test drove it down the road and my universal joint broke and my drive shaft fell off.

Also as a side note; I noticed it would seem to idle fine before until I brought the engine up to about 3000 rpms, then it would stay idling at 1500 rpms. I have sprayed all around the carb and intake with carb cleaner to check for vacuum leaks but did not notice anything. But I have never looked for a vacuum leak before so I dunno.. .

So bascially I think I have wrapped myself in a huge mess. And sorry for the long post. . .I am just gonna take this one step at a time now then take the carb to a garage I know that deals with old cars a lot.

Edit: The pcv is on the passenger side and the breather is on drivers side. The hose from the breather goes into the back of the carb like my old setup, I think.