hi, my daughters 53 plate has developed a problem, it has 45 k on the clock, intermitantly when driving, you get a slight misfire, then the dreaded engine management light comes one, it still drives, but then lacks power, as though its running in some kind of slow mode, if you stop, turn off the ignition, it goes back to normal, its not doing it all the time, it made a 120 mile journey last saturday, and didnt put a foot wrong, I've had my obd2 code reader connected, with the engine running and the management light on, and it doesnt read a fault code, its so frustrating we're thinking of getting read of it.
any help would be appreciated

Its allways best to get a diag done at Fiat first, they might find something with there equipment, most likely though its a faulty sensor this is just a guess maybe the boost pressure sensor.