The Administration may have to move faster than it would like to formulate both trade and aviation policy. By Feb. 3, the Transportation Dept. must rule on a dispute between Japan and United Airlines Inc. At issue: how much control Tokyo can impose on flights to third countries with an intermediate stop in Japan. Transportation is expected to accept United's argument that Tokyo's insistence on control violates an existing treaty. The open question is just how tough the Administration will be in imposing retaliatory sanctions on Japanese carriers flying through the U.S.