ok i have an 04 astra gsi turbo.. it has 57k on it and standard turbo.. it uses no oil or water and doesnt smoke. the problems i was having is that it felt a little slow on power and wavey especially when cold. but now its thrown on the engine management light and gives the code p0530 which is something to do with the aircon but the aircon is working fine. now the car is very slow and wavey and using fuel like mad. so its in limp mode.. can anyoine suggest what else could be causing the code and wavey power??