Urgent help please: Plumbing of 20vt PCV system confusion

Hi guys,

I found a rubbish pipe in my PCV system so went to change it and found something which confused me. As in the picture below, the car came with the system vented to atmosphere. However there was a T-piece in there with a pipe (the one I was intending to replace) running to the top of the oil filter housing. When I took the pipe off though, the T-piece had a blanking plug inside! So the pipe coming off the oil filter housing just mated up to the t-piece, but was blanked off inside anyway…

Is this the way it's supposed to be?

Ok, so I was told that the blanking plug should NOT be there, so I have removed that. It also had the PCV valve bit still in the line, so took that out too (so now there is just a straight through hose from the top of the oil filter housing to the crank case breather, vented to atmos.)

However, now that I've done this, the car definitely idles worse, quite lumpy. It's also terrible now at low throttle input, lurches and kangaroos all ovr the place Also the boost itself feels much more violent than before. Last smyptom, at idle if I rev it, after putting my foot on the throttle it "burbles" around 1.2krpm and hesitates there for a tiny fraction of time and then actually revs.

Does this sound like maybe a collapsing hose? Admittedly the hose I used for the PCV is not proper silicone, it was a stop gap solution.

Or anything else it could be? Weird that is ran so much better with that random blanking plug in it…