skipping A and B's

Im working on getting RatOS running on my 2.4. I am running LDO 42STH48-2804AH's for the A and B. Those steppers are not in the setup wizard so I picked the 2504's. But Im still losing steps in "Performance Mode". Does anyone know if there is a way to fix this without replacing these steppers? I know they are not the "Optimal" steppers but they are very good steppers.