Similar problem on 156 2.0TS. First it was difficult to start when hot. Then would cut out when slowing down for a junction or roundabout after cruising. Would not restart until the car had stood for "a while".
The AA diagnosed it as crankshaft sensor. Alfa dealer diagnosed it as crankshaft sensor. Dealer fitted a new one. All was then hunky dory.
I hope for your sake it is the crankshaft sensor and not the cam sensor. As already mentioned, the cam sensor is on the side of the head behind the exhaust cam pulley. Probably a cheaper part, but a lot more expensive labour to change - unless you do it yourself, then the cost is merely skin and sanity. You would probably need the inlet pulley off too as the sensor wiring is located behind that to a connector hidden somewhere behind the PAS reservoir and under the inlet manifold. Reassembly would require a full engine re-time, so you may as well do all the belts tensioners while you are in there.
Last edited by williamt73; 02-06-11 at 06:50.