The federal health insurance exchange that serves consumers in 38 states will open for browsing Sunday. The site will be faster and easier to use, and it will allow consumers to calculate their out-of-pocket costs, Department of Health and Human Services officials said Friday. A key feature of HealthCare.gov won’t be ready, however. Consumers who want to search which doctors and prescription drugs that different plans cover won’t have that new tool available yet. Officials wouldn’t commit to whether it would be available before the third open enrollment for the Affordable Care Act exchanges starts Nov. 1.