Preheat oven to 400 degrees.
Add oil to a large skillet and heat over medium-high heat.
Dust chicken with flour, and season with salt and pepper.
Add chicken to the pan skin side down.
Cook until the outside is caramelized. 3-4 minutes each side. Remove from pan and place in casserole dish.
Add onion to the same pan and saute 3-4 minutes.
Stir in the raisins and garlic and continue to saute for 1-2 minutes.
Deglaze the pan with the Marsala, scraping up the bits from the bottom of the pan.
Stir in the tomatoes, chicken broth, vinegar, sugar and oregano and bring to a boil.
Add the olives and the capers.
Pour the sauce over the chicken in the casserole dish.
Cook for 30-35 minutes or until the chicken is no longer pink and the juices run clear.
An instant-read thermometer should register 165 degrees near the bone.
Garnish with parsley.