Its a 1.9dg with the pierburg 2e3 carb.
When I start it, it runs rough for a short while and smokes (blue smoke), then it gradually clears itself and starts to rev up as if I'm pressing the throttle. It will keep revving higher and higher until I'm sure it will end up running flat out. If I load the engine the revs drop to normal level, until I let it try and idle, then they will race up again. Most of the times I've started it, it has done this, but a few times it has behaved more normally, including, typically, when I picked it up, when it was running pretty well

Am I right in thinking its some sort of carb issue? It doesn't seem to be vacuum lines as that was my first port of call after previous carb issues on my MK2 Golf were caused by split lines. They looked fine and the few suspect ones I've changed.
Any ideas and advice would be great as I need it running right to diagnose other potential problems!
In case that makes a difference it had been standing for 5 years or so before previous owner got it.