I have the car 10 months now and after having it 2 months it started chugging or stalling when the rev crossed 3000rpm.. The car was serviced the next day and nothing found wrong until a week later it did it again.. Took it back and nothing seemed to be wrong.. Now 8 months later its doing it every day and all the time.. Took it in for service this morning and it got a new feul filter and all that but its still doing it.. The garage isn't a main garage but said they put a laptop to it and said that the fuel sensor on the end of the rail is gone.. But i went to a ford dealer afterwards and they said they have never changed 1 yet.. The sensor costs 260 plus VAT and labour on top so don't want to get it done if its not is.. Any ideas what is wrong??

Thanks in advance
Greg