If you've washed that many times, I'd say it's got to be out of your hair. Does MOP have protein? It sounds more like a protein problem than anything else. I personally wouldn't wash it anymore...maybe a moisture DT and see if that helps the stiffness?
http://public.fotki.com/SunshineGrrl/ pw: drama
This area is under construction as my hair type changed and nothing works well for me. I shampoo, I condition and pretty much have done nothing but chuck my hair in a messy bun for the past oh...year? Yeah, I'm that lazy.

No...going no-poo or CG does not work for me. It leaves me overconditioned and oily in a second no matter what I use, so that's not what's not working.