Help! High idle when starting from cold!

Well as soon as you put a VW up for sale…  they throw you a problem! 
Upon starting my 8v gti 1983 k-jetronic… Golf.
It revs at around 25000 not the usual 10000.
Now I've had the auxiliary air valve off, cleaned it… (it was open when removed) which is good I believe?
I removed the fifth injector and gave that a clean. 
Upon removing the Auxiliary air valve I found a small crack/hole in the small rubber joining pipe that goes to the solid metal pipe that connects to the flexible black join to the inlet manifold/throttle body.
Now I've replaced that… still same issue. 
What am I missing?
Could it be current to the air valve? 
Also there is a vac pipe below the idle control screw in the throttle body… is this where the thin black pipe from the distributor vacuum connects?
I used to be able to do all this years ago but I think old age has caught up… 
any help gratefully received
Thanks