I had a similar problem last month with my 1998 Camry (106,000 miles), hesitating and even stalling while slowing down to turn or stop. This occurred after driving for 12 to 15 miles. I would have to shift into neutral and keep the RPM's up to avoid stalling. While slowing down, you could see the tach needle swinging up and down.
When I first took it to the shop (a local Toyota dealer), they could not duplicate the problem. But they suspected it was the EGR valve or some other type of sensor. It's fairly expensive to replace these parts and they suggested that I bring it back if the problem returns. Well it did, on the way home from the shop. After testing it for a couple more days and still not being able to duplicate the problem, I told them to proceed with replacing the EGR valve and the coolant temp sensor. Problem solved, and the car has been running fine ever since.
After researching my problem on the internet, including this site, the problem primarily pointed to the EGR valve. However, similar problems occurred with other who had replaced the coolant temp sensor.
