My astra is cutting out, can anyone help?

My 1997 Astra 1.4 reguraly cuts out when engine is not fully up to temperature. It start's fine from cold, but if it stops or cuts out shortly after it will not restart. Once up to full temperature there is no problem.
I have changed the following with no success, distributer, HT leads, coil and module, fuel injection relay and have also blown out the fuel injector.
Any suggestions will be much appreciated.