2002 Alfa Romeo 147 cutting out

Transmission problem
2002 Alfa Romeo 147 6 cyl Two Wheel Drive Manual

Hi,

My car keeps cutting out on journeys, it started last night and cut out 5 times in 3 hours. Everytime it cut out I had to wait 15 minutes and then it would generally start and go again. No warning lights are on the car. It cuts out more at slow speeds? Please help!