When the carburetor is cold and the electric choke is on it's richening the 
mixture; since your symptoms apparently don't occur until the choke heats up 
and turns off I would suspect there's just not enough fuel getting in at idle.
I doubt that the fuel selection has much to do with it (I run E10 maybe a third 
of the time, and I don't need to make any adjustments to compensate when I do), 
but since it does take a slightly richer mixture to run E10 gas I suppose it's 
possible that a slight tweaking of the idle mixture could help if you're 
borderline-lean to begin with. Check that the idle cutoff solenoid is screwed 
snugly into the LH side of the carb and that the wire to it isn't loose. It 
should make an audible click each time the key is turned on.
It could also be an induction leak somewhere - any unmetered air sneaking in 
below the carburetor will make the mixture leaner as well. Make sure you 
haven't got any loose/leaking vacuum lines going into the manifold. `71-`74 
engines frequently develop induction leaks at the intake air seals (the two 
rubber sleeves which couple the center section of the manifold to the end 
castings...changing those is a PITA, hopefully that's not the problem. 

Adjustment procedure for the 34PICT-3:
http://www.vw-resource.com/34pict3.html

--- On Mon, 8/4/08, Moulden <[EMAIL PROTECTED]> wrote:

> From: Moulden <[EMAIL PROTECTED]>
> Subject: [vintagvw] VW ideling problems
> To: "Air-Cooled Volkswagen Discussion List" <[email protected]>
> Date: Monday, August 4, 2008, 8:20 PM
> I own a '72 Volkswagon Beetle, and am having trouble
> with it. She runs fine once I get her going, but has trouble
> ideling when I first start her up, and when i stop. She
> wants to die at stop signs.
> I've checked the spark plugs and timing, and it all
> seems to be ok. 
> I'm running 10% ethanol fuel if that matters. I've
> heard that that can have a negative impact on a cars
> performance, so was wondering if that could affect it.
> Any suggestions on what the problem might be?



      

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