Had a similar fault on three corsas that I know of,every one would lack power and engine management light would come on if you tried to floor the throttle for more power,turned out to be Mass Air Flow meter at air filter,think this is a common fault on these motors,another thing maybe to remove EGR valve and make sure it is nice and free and not sticking.Try and get M.A.F meter at scrappies but dont go to main dealer,costs the earth,think you can get a bosch meter from a motor factors such as TMS or Dingbro saving a few quid.Good luck.
Neil
April 2010