The mixture tweak seems to have helped, though its too early to know if its 100% cured. I'm curious about the duty cycle discrepancy. But since the car runs fine, I'm not feeling compelled to locate and swap out ECUs, etc. Plus I'm a little afraid of what I might find, and/or breaking something else in the process.

The ratio at 2500 rpm hovers around 70%. Idle is now 70-76.

I'd like to find out if any other 1985 380s (86560SEL?) want to be at 70% duty cycle instead of <50%. Or do I own a total odd-ball?

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1985 380SE Blue/Blue - 230,000 miles
2012 Subaru Forester 5-speed
2005 Toyota Sienna
2004 Chrysler Sebring convertible
1999 Toyota Tacoma