As a Pastor is it better to use my mileage as a business expense or as an adjustement to my SE Tax for my Housing allowance? Why is the refund different?

I used the work sheet to populate the data, but when I used the same mileage from the Business Expense section to amend my tax liability for my SE Tax from my Housing allowance, my refund dropped- even though I added more items with it to reduce my Tax amount. Standing alone, the same mileage from the work sheet without adding any the other credits was $120 more. So, should I just re-enter the Mileage data & delete that data from the section to amend my Housing allowance? Does the Denson rule does not aplly to this