More Help please

[alfisti@domain.elided]

Hello again gang, some help with a 2l straight 4 Dell Orto carbed 
engine with 126k miles on it  would be appreciated.

The engine is great at anything over 1000 rpm, right up to 5.4k (wife 
imposed redline)  Plenty of power, willing etc.  A couple of probs.  
The idle is *really* rough.  When cold, without full choke it will just 
stall.  When hot (right up to temp) it's just slightly lumpy.  Starts 
first time with choke tho.
My thoughts are an air leak, any other ideas, and suggestions of 
how to track it down, if that's what it is.
Other probs to consider:  PO has wrecked the head of the number 
3 cylinder mixture adjustment screw.  Can I get it out with a stud 
puller, and replace, or is the screw odd in some way.  (Currently 
cylinder 3 has not been adjusted for 25k miles)
How much 'suck' should be present on the vacuum advance 
module.  When the hose is disconnected, and a finger stuck over 
the pipe in the manifold, you can fell a *very* light suction, but 
nothing that I think would pull the vacuum unit.  Should there be 
more, also should pulling the hose off change the idle speed at all?

Thanks in advance fro any help suggestions.
Catman

Tyger, Tyger Burning Bright
116 Giulietta 2.0l

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