Recently acquired my first Subaru ever..... an 87 GL wagon. It had sat for the past few years; has 191000 miles with about 60000 on a newer engine. Engine seems to be running well (after some carb cleaner) but automatic transmission seems to slip after extended driving. Also, it seems to take more speed to get it to shift; it goes into second around 23 mph, and into third around 47. Do I need a new transmission, or is it possible that a flush would help?