if your feet are lined up ok, double check to make sure ur hips are also lined up ok..sometimes my feet will be on line, but i will open my hips without realizing it and end up pulling and hittng out to in. if i focus on straightening my hips it goes much straighter... but thats always takes 16 holes to realize.
just had them today on the front 9... for me it wasnt ball position since thats the first thing i check, but it was the fact that i was putting more weight on the balls of my feet than the heels, and this made me lean forwards during the swing. i adjusted to balance more on my heels or 50/50 and the shanks went away
what always helps me is practicing the stroke until i know its the speed i want.. even if i take 10 practice swings... then i make the swing and just trust i have the right speed... if i try to adjust at the last second i skull it.
also make sure ur practice swings are barely grazing the ground.. if not.. keep taking them until u do.
not sure if it applies entirely but you can strengthen your ankles and shin muscles. you can sit on a chair and twirl your feet in the shape of the letters of the alphabet.. you will feel some burn in your shins.
also.. stand up on one leg and balance with ur arms out, then try with no arms out, then with eyes closed... for as long as u can..really helps with balance and strengthening stablizers in your legs.