Hi Roger,
I never use EcoFlo waterbased acrylic dye. I tried it, and had bad luck streaking as you noted. I've seen others online lament working with it. I think James may have had success with it though, so he may be able to share the secret.
I use the Fiebing's Pro Dye mainly, and stick with that. I works well with staying power, and doesn't have issues with oiling or top finishes in my experience.
For application, the person who showed me instructed that you thin the dye first, and apply it in a scrubbing motion with a scrap of sheepskin. I buy those scraps by the bag-full. Let that coat settle, and add another in the same way. Build up tp taste. Make sure and wear an apron and disposable gloves. Oh yes, I blot the wet sheepskin scrap on a paper towel before scrubbing into the leather, thereby preventing a dark blob in one spot (hopefully).
All of that said, I dye all of my parts before sewing. In fact, I usually dye before cutting to final size to minimize dye variations at the edges. If you are doing dye work after sewing, you'd better coordinate with someone who also dyes that way.
Hope this helps. God Bless, Marc