help needed!

[onedayTM]

hi guys dont know whether you might be able to help me. My sons fiesta M reg 1.1 petrol HCS engine with single point injection has been running with what would seem like a sticking throttle, you can take foot off pedal and it keeps going, not all the time, now and again. He never sorted it and now it keeps cutting out. It will start and run but as soon as you try to put your foot down it dies and then will not restart for some time. took it to garage and had it tested, no air leaks but map sensor fault was showing on system. He suggested a replacement but wouldn't say it would fix for sure. I put new sensor on and still the same, any of you guys got any suggestions?
cheers
tony