Alfa Romeo Repair: POOR IDLE, air flow meter, component specs

Question
HELLO I HAVE A ALFA 156 2 LITRE T-SPARK AND HAVE A PROBLEM WITH THE IDLE IT HUNTS FROM BETWEEN 1500-3000 REVS I HAVE HAD THE TROTTLE BODY AND AIR FLOW METER REPLACED BUT STILL DOES IT  

Answer
This is the classic description of an unwanted air leak.  These usually are not obvious: it can be a split in one or more rubber boots or tubes, it can be a blown out gasket, it can even be a sticking idle speed motor.  If the grounds or connectors are corroded it can even be caused electrically.

How are the vacuum hoses.  A detailed physical inspection of the intake system is step one.  I am in the usa and do not have access to the electrical schematic for this system so cannot give specific component specs to look for.  If you cannot find a physical fault try blocking off the air to the throttle body and see what happens. And then block off the idle air control... 3K rpm seems excessive for something like faulty injectors causing poor idle quality and thus the idle control overcompensating.