2003 Vauxhall Vectra over revving loss of power

hi ive been having trouble with my vectra 2.2.It will drive fine then suddenly it loses power and the revs go upto 2500-3000 rpm and then engine management light comes on.I then have to pull over turn off the key and wait a few minutes,when i start up again the revs go back to normal until the newt time.This can happen once a day or once a week but its so annoying. Can you help please .