Ok I'm trying to catch up and understand the wideband thread.
I see that rolling on the throttle abruptly will make Motronic leave closed loop and go to the richer open loop map.
At that moment I can enjoy the slight increase in air throughput due to slightly (1/3) shorter valve lash.
At cruise it burbles along, obviously lean. Won't idle very long, have to goose it every few seconds.

Ok, pulling the cat code plug puts me in open loop all the time, and guess what it runs much better through the whole rev range.
It idles.
It never goes into closed loop though, so the cat converter gets happy only when decelerating.
It's not easy being green.
Perhaps a circuit that "pulls the plug" at idle, so it will idle at stoplights?
Maybe charge a cap with the tach signal...