engine not running well

I have a problem that when the engine idles its fine. As soon as I rev to about 2500 it begins to hunt, like its not getting fuel or spark correctly. I have replaced the carburettor, distributor and ht leads. It does the same thing when driving at a constant speed and rpm. It is a Golf MK1 1600 8v.

You don't get petrol from Tesco or Morrisons by any chance do ya?! Sorry couldn't resist  :wink:

No we don't have that fuel in South Africa. We have what is known as lead replacement fuel.