Can you elaborate on the problems you're having with stopping/standing still? Are you trying to get her to ground tie? Or is it a leading problem?
For feed, I'd avoid grains. Drafts in particular are prone to a number of issues, ranging from founder to shivers, etc, that are made worse by high starch/sugar feeds. I'd start off with 1.5-2% of her ideal body weight in hay, plus either a ration balancer or vit/min supplement. Watch her weight closely and if she starts dropping, add more hay, rice bran, or beet pulp. Many drafts are surprisingly easy keepers, though.