head replacement

[merc]

We replaced the head gasket in a 00 1.4 opel astra and manifold gasket, we then started the car and since when the car is about 10-20sec started she is reving to 1000 on her own we have doubled checked the manifold gasket twice and the trottle housing, all the car electronics have been checked by an opel garage and clear as prefect, we would greatly appreciate any advise

[Bat2105]

All the major gasket manufacturers (British gaskets/Payen/FAI) have technical helplines, give one of them a try. Payens number is 01274 723481