Laguna 1.8 sport estate ecu problem?

The ecu could be the cause of the problem, if one of the coils has failed and spiked the ecu it will no longer be able to control that pair of coils or the injectors for those two cylinders. As for repairing it there are a couple of options. One is to obtain a second hand ecu and send it away to have the immobiliser code erased from the ecu memory, this will then effectively be a blank ecu and will be coded to your car when you turn on the ignition. The other one is to obtain the ecu, the immobiliser ecu (decoder) and the key fobs. All the parts must be from the same vehicle as they all hold the immobiliser code in their memories. Hope this helps.