Before you replaced all that stuff and spent all your time you should have considered going to a dealer.
We (4 drivers) have driven almost 750K miles in 4-740s, 3-850s, 2-XC70s, and a 544, and never had our dealer repair more than one item.
It sometimes makes me sad to see great folks take so much trouble when a relatively small bill will do the trick.
BTW - when the ECU went in our '90 744TI died I found that my favorite junk yard which had more than 800 Volvos could provide 150 CPUs for NA 700s, but NONE for a turbo.
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