I developing a stand alone DFCO (Deceleration Fuel Cut Off) module for my truck, it's work very good and easy to setup. Still under observation.
Set to 1300 RPM and 25kmh cut off threshold, smooth transition
Not to put down the effort you have put into this, but DFCO behavior is something that can be modified through engine tuning software.
Not every car have DFCO feature, and not everyone have access into the tuning software.
I have 2001 opel blazer that don't have dfco feature and the only way to get access into the ECM setting is using those expensive TECH-1 tools, that's why I develop this standalone dfco module along with "i-VMT" (Intelligent Variable MAP tuning) device in a single box, it's all analog device, no need computer/software tuning to play with it.
Target is 10 to 20% fuel efficiency without loosing power