All of a sudden, it feels like I am starting out in 3rd (2nd?) gear when in Drive. It was fine until a couple days ago. Only 26,000 miles and fluid level/color are fine. It also sometimes doesn't want to shift out of whatever gear it starts in. Everything works fine if I start in 2 or 1 and switch back to Drive at about 15 to 20 mph. Any ideas what is wrong? Like to avoid my first ever trip to the dealer, if possible. Thanks!!