Trim fat from roast. In a small bowl, combine caraway seed, marjoram, salt and pepper. Rub all over roast.
In a large skillet, brown pork roast on all sides in hot oil. Drain off fat. Place meat in crockpot. Add the water to the skillet; bring to a gentle boil over medium heat, stirring to loosen brown bits in bottom of skillet. Pour skillet juices and vinegar into crockpot.
Cover and cook on low-heat setting for 8 to 10 hours or on high-heat setting for 4 to 5 hours. Remove meat from cooker; keep warm.
GRAVY: Skim fat from juices; measure 1-1/4 cups juices (add water if necessary). Pour juices into a saucepan; bring to a boil. Combine sour cream or yogurt and cornstarch. Stir into juices. Cook and stir over medium heat until thickened and bubbly. Cook and stir 2 minutes more. Slice meat and serve with gravy.