Scirocco Register

I have recently purchased a gt2 g reg. It had a rotten fuel filler neck so I got a new one and fitted. The car runs fine on first start up with auto choke doing its thing but once hot drops to 500rpm I decided the little screw on the wax state was the idle screw so adjusted this so it idles at about 1000 rpm.
I though everything was going well so took her for a spin in which she saluted and stalled at 60 (traveling up hill). After a minute she started fine turned around and she was good to 70 down the hill. Same thing happend second time round so I decided poor fueling under load.
I adjusted the mixture screw and tried again everything was fine but when travelling home through a 30 she started lurching stalled and wouldn't start. I then got her started but 2 mins later the same thing happend.
What could this be???
I now know the correct method fir adjusting the idle could I have messed things up there?
There's rust in the tank but shouldn't that affect it more when it's under load not cruising?
Really need help sorry so long winded but wanted to be specific.

If you've got rust in the tank then that is almost certainly the cause.

like edmundator says you're going to have to strip the fuel system down to make sure theres no rust in the system.
start with the fuel tank by taking the level sensor out because the pickup pipe is well know to get blocked by debris like rust.
next blow through the fuel lines from the engine bay end to the tank to make sure the fuel lines arent blocked by debris.
lastly change the fuel filter as that will have crud in it.
if that doesnt fix it then there will be crud in the carburetor. i would not advise taking the pierburg carb apart unless you know exactly what you are doing because setting it up to run properly after stripping is an art.

Is the warm air feed intact? been having issues with Pierburg myself , they are great fun

What my old scala did sounds similar to what yours is doing. It was suffering fuel starvation as the strainer on the end of the pickup in the tank got blocked with bits of rust. Letting it sit for a few minutes and / or taking the fuel line off and blowing back into the tank would see it running fine again for a bit.

If it's your filler neck rusting then it needs sorting. If you leave it, eventually you'll get water getting into the tank and giving you more problems. If the tank itself has rusted inside, it's gonna need a new tank if it's bad, or you might be able to get away with treating it to some frosts tank sealer

Yeah Im hoping it is just the rust getting on the pick up I've had the sender out that's when I saw how much rust was left. I had a rusting fuel neck which I have just replaced. Although the car has got a new pump on it I decided rust can't be doing it much good so got now pump. Clear bowl filter so I can see if any rubish gets in again and vapour separator tanks going to get a fuel clean then fit all new bits. She runs like a dream tho happily get to 70 but won't cruise at 30 so that's why I fort carb. I've now read about the high idle and low so going to redo that as well and check all vacume lines. if it doesn't sort it then I'll give the carb a rebuild.

No warm air feed isn't fell off landed on alternator belt and can't say that done it alot of good tbh. That's next on my list to fix want it all back original. Picked her up for £300 and spent less than £120 on it and should with a bit of tweaking have an mot soon.

maybe sound silly but try driving around with the fuel cap off. i had a similar sounding issue with mine. maybe be down to the tank no being able to equalize pressure so a vacuum is being created and the pump struggles to pick up fuel.

Check the rubber flange which the carb sits on, they can crack and let air in. Give the carb a wobble while it's ticking over and listen out for any change in idle speed.

Looks like this.
http://www.ebay.co.uk/itm/MK2-GOLF-Carb ... Swu4BV3atJ

I know rust in the tank is the big obvious one and that's what I'm thinking the main problem is but I only ever work on large diesel engines so not clued up on carbs and wondered if it sounded like a common problem before I started going down the wrong path.

I've already checked that and no sucking sound or note change

Literally then only reason I asked was because I wad being lazy and didnt want it to go down the route of tank off but I think it's going to have to be first port of call.

There is an inspection hole in the top of the tank which you can get to if you remove the base of the back seat, you can then look in the tank and check the fuel pick up. You can clean some of the rust out by fishing around with a magnet then clean the magnet off then leave it in the tank to collect any more rust floating about.
To remove the fuel tank you have to drop the rear beam.

If you go to removing the tank, be very careful undoing the nuts to drop the rear axle. Shearing one (or more) of the studs will be a right pain. Whenever I've done this I've heated them up with oxy-acetetaline first to free them up.