I cured it by stretching, losing weight, moving to Zero Rise (heel to toe) shoes, and going barefoot as often as possible. The stretching should not be limited to the foot, but must include the calf. The problem sometimes begins with tightness behind the knee. That pulls everything all the way down, until your foot complains.
Look into "mid-foot landing". Turns out that the big, wide heel on runner's shoes actually forces a heel first landing. If you do away with that, you can do a mid-foot landing, which is what you do when you are barefoot. That will feel a whole lot better, if you have plantar fasciitis.
If you stretch all day long, and wear mocassins with no sole, your feet will get stronger fast.
I just ordered the Merrel Vapor Glove... with rewards points, cost less than $30!