Thank you all for replies. I have just checked and ECM is indded indicated in ViDA as terminating module. I will have to check that as well

Both the upper and lower bolts are replaced on reassembly per Volvo.

Upper bolt 30 Nm
Lower bolt. 25 Nm

The rough running might be related to the ECT (Engine coolant temperature sensor). The connector for it can corrode or the unit fail. IT is one part that is recommended to use Volvo OE (expensive) as there has been no aftermarket one that has proved reliable out the box consistently. It would explai...

100 miles is nothing. Why risk the death of your son like that?

Post away. The devil you know is always better than the devil you don't. That said, sometimes there's a speed itch one needs to scratch, and for that he may trade reliability for handling. It's all in what you value most. There is no right answer. Meditate in the sun and your choice will come to you...