As has been said it is the swirl flap rod.
But I have the same car as you and mine was loose and I managed to fit it back on about 3 weeks ago and its still fitted, the actuator operates number 3 cylinder flap from underneath, this in turn moves the other valves via the rod that locates on a small pin on each flap. Before you try to refit it make sure the 3 valves 1,2 and 4 move freely by turning them, they are about the size of a 10 pence with a small pin about 4mm thick on top. number 3 wont move as it is attatched underneath to the actuator. If any wont move then you definatly need a new manifold but if they all move and the plastic cups on the rod arnt worn too much (the rod isnt available seperatly) you can refit it by lining the position of the pins up with number 3 and tapping it into place.
It is a really fiddly job, I removed the injector manifold to make it easier but was still a pain to line them all up.
I am expecting to have to get a manifold if the rod comes off again.
The cost.... Manifold is about £200 and it looks a pain to fit as I think the injection pump needs to come off for the manifold to clear the studs which means cambelt off, typical because I've just changed mine but at least I'll know how to do it second time.
Do a google search for vectra swirl valve/flaps, its the same engine and manifold and there is far more info about for the vauxhall than the Alfa.
There is a guy advertising on ebay to fit a manifold to either a saab or vectra with the same engine for £160 labour
My car wasnt starting very well so I ordered a set of glow plugs for it, I notice the rod was off whilst I fitted them but didnt have time to fix the rod, it was still starting badly with new plugs but when I refitted the rod starts much better now
Last edited by JON156VELOCE; 15-08-11 at 21:51.