I live in California and it's time to get smog done but smog shop won't give a pass since the previous owner installed aftermarket intake pipe on it and I was told that it should be stock or need sticker for carb or something so I decided to swap it to stock intake pipe however, as you can the picture below, my car has oil catch can (UPR brand) and it has 3 nipples and the previous owner 2 hoses for pcv (back of the valve cover) and one for intake pipe and he made the hole into the intake pipe.
when I installed the stock one, I left the one nipple opened on oil catch can that was connected to intake pipe hose and once I started up the engine, the idle was not stable and good. Do I have to make the hole on stock intake pipe and install like the one before? Please advise. I'm not good at mechanic stuffs so please don't think that I'm asking a stupid question lol.

 

installed cap and problem gone.