Have you gotten a video tape of yourself running? It’s one think to feel like you are doing something a certain way (like not splaying) and another to see on the video tape. (I am assuming you did not check this way) Take a front-to-back video and look for your foot landing. You can also check yourself as you walk along a stripe or line in the road or walk, with each foot to either side, and notice if your feet are moving parallel to the stripe. If not, be sure to pick your whole leg up and rotate it medially at the hip to make the correction.
Above all, make sure your pelvis is level and your low ab muscles engaged enough to stabilize your pelvis. Look for that on the video as well.
Keep us posted on how it’s going.
Certified Chi Running and Chi Walking Master Instructor