I have a 16v 1.2 2000 bravo. I have had the intermittent stalling problem, this was rectified by fitting new stepper motor. The car went in for an MOT last year, where they had to change the cat. When i went to pick it up the car was idling at 3000 revs, left it with them picked it up next day, all was fine other than it being noisier than before, didnt think anything of it. Checked something else after and found they had put a screw to hold off the stepper motor, not impressed but left it as car was running ok. Problem is that car has been running worse and worse lately and nothing i can do to seem to get it to run as it was before cat change. I have tried numerous different thicknesses behind stepper including nothing and cant get it right. Any ideas as i am completely out of them. :bang::bang::bang::bang::bang::bang:

Have you tried a reset of stepper motor with Examiner OR diagnostic lead and fiat software?

Wouldnt even know where to start and i dont own any diagnostic stuff

From what i have seen on my fiatecuscan, the stepper motor needs reseting if has been removed or replaced. The garage probably didnt do this so used a screw to position it! All it does is go in and out either restricting or derestricting the air flow at idle (with throttle plate closed).
where do you live? I have cable and software to check it.
Why was cat replaced?