What Cougie said - even more so - the constantly changing angles of your foot plant on trails negates any notion of motion control. In any case, there is evidence that motion control shoes do nothing to change injury frequency. Maybe just try a trail shoe of the manufacturers you like, in the hope that the general volume, upper shape, last shape will be what you like.
I wouldn't have any snacks at all, especially if it's a snack to get energy that doesn't have too much energy! Also, I wouldn't look to snacks to ensure I were eating essential dietary items. Depending on the race length you will get through most of glycogen stores in muscles anyway (e.g., marathon). IMO most of coping with longer distances is down to natural ability and training. It could also be that you are not having sufficient rest between hard sessions or you are not tapering before a race. In short - just what Cougie said
There's a really good review of the medical issues, diagnosis, stretching and strengthening at Runner's Connect. I wouldn't expect results after a couple of weeks. Even assuming the diagnosis is correct, you will need to follow the treatment diligently for quite a while, as indicated in this article.
You say you have changed shoes but not to what. For example, a so-called motion control shoe could have more arch support that is in fact rubbing. There is no evidence that motion control shoes prevent injuries, so if this is the case I advise a neutral shoe. On the other hand, since you mention the join between shoe and insole, maybe you haven't got a shoe with a wide enough last. Check that out too.