Hope you get it figured out, too bad throwing the towel in, but understand that at some point of frustration, your nerves are shot because everything "checks out", and you just have to take a step back and have another brain and set of eyes on it and then "poof" some absolutely obscure thing turns out to be the problem.
Hope you get her back on the road soon.
Like the white letters out on the tires, think my next set I'm gonna put em out too.