I'm not sure about the pouring back and forth, I don't do that. But for a 1.081 beer, getting enough oxygen for the yeast is an issue. Pouring through the strainer may be enough.
That's a big beer, so that will affect attenuation, too - as the fermentation continues, the environment will get more hostile for yeast (because of the alcohol) as they keep trying to do their jobs.
Lowering the fermentation temps as you go is counter-intuitive to me. As things are getting harder for the yeast, you make it even harder by chilling them. Plus, the off-flavors associated with higher fermentation temps mainly develop early in the fermentation.
The crystal 60 is going to add sugars that won't ferment. I've not used Carafa II, so don't know if that is true for it, also.
Before giving up in despair
maybe try a nice, regular sized APA or brown ale, something around 1.050, keep the crystal at a minimum, reverse your temperature regime, try a US-05 (known for super attenuation and according to some doesn't require oxygenation) and see how it goes.
I can hear your frustration. Let us know how things go for you.
Edit: Have you double checked your thermometer for accuracy, that you are accurately measuring mash temps?