If you haven't yet, start with a clarifying sulfate wash to get rid of the build up. If you stop using products with non-water soluble cones then it should help with the quick build up you seem to be experiencing. Course hair naturally has a lot of protein and I think most of them avoid protein in their products. Hopefully someone with that kind of hair will chime in. Everyone's hair is different, mine is very fine and theoretically should really like protein, but I can't use most proteins and I can NEVER use wheat protein. When I over protein, my hair feels like straw and it breaks like crazy!

From what I understand, it is not uncommon for low porosity hair to be dry. My low porosity hair makes it hard to absorb moisture and when I started using more water based products with LOTS of moisture, my curls perked back up. I still struggle with frizz, but I'm starting to think I will always have at least a little. When I use products with too many emollients or heavy oils they just sit on my hair and even at the end of the day it still looks greasy.
I have to air dry....no diffuser for me, it just causes more frizz.

I also have learned through trial and error that I cannot use any leave in products with glycerin. I am okay if I use a rinse out poo or condish once in awhile, but my hair is happiest if I don't use any at all. If I use glycerin in a styling product, then my hair feels coated, gunky, and tangled by the end of
the day. It's really a bummer because there are lots of popular styling products on the boards with glycerin. When I started avoiding glycerin completely is when I found out that I could add some small amounts of protein back into my rotation. The jury is still out on other humectants for me.

Before you decide what products to try check out the boards for curlies with similar hair properties to your own. There is also a lot of GREAT info on the forum named "Newbies". One way I have found great info is to do a properties search. For instance, you could type in: "course, low porosity, 3A hair products" and do research on the links provided. If you find someone on those links with similar hair properties you could see what they like to use and start there. Lots of us have the products we use in our signatures. I got a lot of ideas by "stalking" certain people with more experience and similar hair properties to myself. Sorry this was so long! Good luck in your search!
3a, baby fine i/ii, low to normal porosity, protein sensitive
Mod CG since 5/12, from rainy Western WA
dislikes: glycerin, wheat protein
Likes: moisture, Mag Sulfate
Poo: Elucence Moisture Acidifying Shampoo
Cond: CJCR, DB pumpkin seed, TJ TTT, Elucence MB
Protein: one & only Argan oil hydrating mask
Style: UFD curly magic, Sweet Curls Elixers flax seed cream and HHG (Etsy)