Rough idle?

Got a bit of a rough idle, it's dancing around between those two notches making things shake. Sometimes it behaves itself and idles at 900 rpm and feels great but sometimes it drops a bit below and dances between 750 and 800 rpm. What could be the problem? 

Vacuum leak maybe? Check your lines'for cracks and splits first, nice and cheap to replace too. 

Yeah that's my first port of call mate. I'm having a go at that first. 

I've got this off but seems to be blocked at the centre part where they all connect. Is it supposed to be? It seems like a diaphragm of some sort. 

Looks like a standard T piece to me matey, shouldn't be blocked. 

When I got my 1.8GTI running it was all over the place as well and I had a lot of vacuum leaks. Those small rubber hoses you pictured, mine looked a bit ropey and frayed like yours and inside they were perished so I replaced them. There is a few of them as they go down to the vacuum advance on the distributor as well. Also check the idle adjustment screw, there is a rubber o-ring on there that goes hard and leaks causing idle speed issues. Also check your breather pipes, mine had small cracks where they joined the rocker cover which also caused idle issues.

I've just sorted out my vac pipes now just taking it for a drive to Asda lol need some munch. Doing idle came back when it was warm. Is this a symptom of the idle screw being faulty im guessing you can buy a generic pack of o rings from halfrauds. Pop one on. Stupid question. Stupid question where the daffodil is my idle screw and how do I remove it. You seem to have changed it yourself at some point by the sounds of it. 

Ps thank you very much 

Picture of my idle screw and o ring at the top of this thread.
https://vwgolfmk1.org.uk/forum/index.php?page=topicview&id=big-block-injection_2%2F1800-dx-idle-low&=

Approx size of the o ring, it's a bit tricky measuring a rubber ring.  

Outside diameter


Inside diameter.

Wow good effort Haha i bet it is that you know! I removed all my injectors and they had brittle plastic seals round them I literally had to smash them out, I bet they are in the same condition as the idle screw 

When you fit a new O ring smear a little grease on it before fitting so it slips on easily.

Those braided hoses for the vacuum system don't seem to last long, I replace mine every few years just to be on the safe side, I bought a meter of the stuff so plenty left to do it a few times.

I think you may still get the genuine VW stuff but I don't think it's cheap?

I picked my hose up a VW show for not much money.