Keep in mind that at that speed the stock speedo is high by about 3.5 to 4 mph. When I am at 2000 rpm in high gear, I am going between 66 and 68 mph via GPS.
What you're describing is the torque converter lock-up. It stays locked up until you slow down enough for it to shift out of 4th lock-up, then the rpm's drop down to a little above idle speed while the TCM waits on throttle position input from your right foot. That's why, if the torque converter is unlocked, when you then press the accelerator again, the engine will rev a little before settling into gear again. This is normal behavior.
Oh, and you need to change your signature - sounds like you already joined the CRD family!
