I have something that you might try for the lope. I used it for a different problem but it may be a simple fix for your problem as well. I was working with a mare that didn't have an extended lope. She took very short, rocky strides. So a friend suggested to me to start to lope her in a wide circle and slowly make the circle smaller. This would shorten the distance between her legs and she would have to move her legs further out to keep up. Of course this was with a younger mare that was pretty sure footed. I don't know how your horse would handle it, but what I would try if it were me would be to trot a circle pattern-then while keeping in the circle pattern but making it smaller try to kick her up a notch, see if she breaks away into a gallop or starts to figure out a slower pace. Just an idea. But only do what you feel comfortable doing with both you and your horse.
~*~*~*~No hour of life is wasted that is spent in the saddle ~*~*~*~