I would ask the ingredients in the conditioner and shampoo. You might want to try going CG, or following the CG method to see if it helps. (Do make sure to do a final clarifying wash before going conditioner-only, though).
About the protein + deep conditioning treatment things:
Protein treatments are intended to strengthen and fortify the hair strand. Since I have coarse hair (naturally protein-rich strands), I very rarely need a protein treatment, and only do it when my ringlets are drooping. Curlies always strive for that balance between protein and conditioner, to improve elasticity and definition, and also keep the hair soft and manageable (and of course, healthy!). Most find that a protein treatment now and then, as well as after damage has been done to the hair, helps bring back the spring in the curl.
As far as deep conditioning goes, I'd like to know more specific hair properties before I give more specific product (or recipe!) recommendations. There are no deep conditioning products that work for everyone. I'd assume your hair is on the porous side (because of the dyeing), and your strands are medium (referring to the width of the shaft), but I can't really get a good gauge.
If a protein-laden conditioning treatment (or a protein treatment followed by a DT) doesn't do anything for you, I would recommend going CG while you get to know your hair (I assume your current products aren't working, based on your post), as the products are often a bit kinder on the experimental side.
I believe there's a link on the newbie forum about the CG method, if you would like to try it.
Hair Type: 3c, Med-High Density, Low Porosity
CG since '09
Low Poo: KC Come Clean
Condish: AOHR, TN (Avocado), TJ Balancing Moisture
Leave in: GDL, KBB
Curl Lotion/Gel: CHS/CK
Others: CJ Curl Rehab, Jojoba Oil