Crank Sensor on mine - Was doing exactly as you state, steadily got worse. £16 from Alfa Dealership, Get it on ramps, slide underneath (remove plastic engine guard) Crank sensor is located at the back of the engine near the bottom middle (Brown Wires I think) - dead awkward to undo, but persevere anyway. I'd lay money on it being Crank Sensor.
Dave Cat, March 2009
