how can i stop my vauxhall zafira 1600 petrol from stalling?

Hi i have got a vauxhall zafira 1600 and it has started to missfire. if i take it on a long run it will run ok but if i just do the school run it will start playing up. it starts ok, into first ok, into second ok, then as soon as i put it into third it will start pulling back and stalling if i turn it off for ten mins and then restart it it will do the same again any help would be appreciated thanks sean..