Building on my previous post, today we installed the new (repaired but new to us) ECU from Sergei in Brooklyn (eBay ID “chkengine”).
It’s immediately obvious that the power of this car is greatly improved!
We’ll drive it a few days and see if this improvement persists. We are cautiously optimistic. There’s still a new fault code (P1135) and I’ll check that every night to see if it goes away or any new codes come up.