Yoga and running can enhance each other in the right balance. However, I got into power yoga at one point (my wife in an instructor). As started to get more into it and very good at it, my legs got flexible enough they didn't feel right when I ran. I started to lose that tight, controlled spring, I used to have in my legs and I lost speed. I actually stopped running for a couple of years and did only power/vinyasa yoga, getting quite advanced.
Yoga helped me resolve some recurrent running injuries I had (ankle, posterior tibial tendonitis). But eventually, I knew i'd go back to running as soon as I was able, and I did. I was able to jump back into running pretty quick, since the high intensity vinyasa power yoga I did, was very cardio and got the heart up, nicely.
Now I only run again, and haven't done yoga in a couple of years. I do miss how good and head-to-toe fit, I felt when I did it.