Why Hunting???

[richandhazel]

I don't think you will have the ISV. Isn't yours an 8V k-jet thats been bored out and race tuned?

The ISV is fitted to the digifant and 16V engines.

[VWnut]

On my mk1 cabrio it is the small plastic box to the left of the engine (looking in from the front). It'll have two vacuum hoses going into it.
When your engine "hunts" the idle valve should be clicking in time with the fluctuating revs.

[essex_lad]

Whoah there lads before you change everything on the engine.

Get the mixture checked and adjusted, mine was running way too rich when I got it and caused exactly the symptoms you describe. Lumpy idling and everytime I dipped the clutch as I came up to a set of lights the rpm's would dive, almost stall then recover !