Letting a horse run to get it out of their system works with some horses, others, they just get hotter, Squiggy & Scotty sound a lot alike, he would run until his heart fell out of his chest. Perfect a small circle, a perfect circle, a flexed circle, try to keep her balanced between your reins and legs, no falling in to the inside, once she is, release the pressure, that is her reward, give her a break & pet her neck so she knows. The circle will control the speed and you will contol her position. Lope her again, once she gets all hot & high headed, back to that small perfect circle, all the balance is lateral in your hands & legs, no backwards pressure on the reins, sit deep in your saddle. I would start at the walk to perfect that circle, when it's perfect and she lowers her poll and brings her back muscles up to you, release the cues, let her walk out. When she does that perfectly, move to the jog, then the long trot then the lope. She sounds like a busy mare, I would give her obstacles in her training, like a bridge, a gate, wagon wheel trotting poles, L back throughs, then go back to working on the controlled lope. Another thing, if for some reason if she gets all frustrated, stop. Do a turn on the forehand, one step, stop, sit there, wait, then another, etc., it gets their minds off forward, and back to lateral and using the shoulders and hind end. The only time I would let her run full out is if you are chasing a cow or in a barrel race because I have feeling if you let her do it in her training, she will want to take the opportunity to do it whenever she feels you "might" let her. Sure you can stop her, but her mind will always be, "when can I run, when when?" instead of "Sure, I will do that relaxed, balanced lope because you asked". Hope this helps, works wonders for all the hot to trot horses I have worked with.