Thank you! I took the car to my regular mechanic since he said he could check out the computer and see if any codes were suspicious, but none were. Since it's a closed system, he wouldn't even be able to change the transmission fluid if he thought that would help. He said the same as you - take it to a dealer and have them make a list of things they would do and how much it would cost. Unfortunately, we put on new tires, rear brakes and front struts before driving the car around to find out there might be a bigger and more expensive problem. I made an appointment with a dealer here in MA and will see what they suggest. The problem doesn't show up until the car has been driven 10-15 miles and gets warmed up. But if it costs $4-5k to fix or replace the transmission, we'll just sell it for parts. Too bad because it looks so good you'd never know it was 15 years old! Thanks for taking your time to give some good advice!