I have a 2002 Zafira and about two years ago had a problem just like yours, losing power up hill, dying out. Brought it to the mechanic and he told me it was a sensor problem. Had to get a new sensor for 200 euro and had to wait a week for parts. Now, two years on have a bit of the same problem, sputtering, losing power up hill. Now they say it is the brains..to be fixed for 800......seem to be able to drive it on a different gear...but still have the fear it will die out on me soon......has a great, smooth ride,(when it works) but too many problems..A neighbor of mine had the same problem too....If a number of people have this problem there should have been a recall!