My Sera has had a bit of poor running recently. A stutter on acceleration, occasional difficulty starting. I decided that it was possibly down to two things, fuel pressure regulator or lambda sensor.
Fuel pressure regulator was changed for a secondhand one, but lambda sensor was changed for a Bosch, single wire universal one from eBay - this one https://www.ebay.co....NzNatnA-lBQifzI
It mentions the original part number 89465-10020 in the cross references.
I was surprised by the increase in performance as well - showing that they degrade with time and that affects the performance of the engine.