i had the same problem and guess what only my reverse is working....

in the sticky at the top of the page titled "common problems", one of the common problem'* symptoms is "hard upshifting, esp. during light accel. Sometimes intermittent." The fix, I believe, is a pressure control solenoid. Sounds familiar because mine has been doing the same thing.

Is, or has the SES light been on? All the TSB refer to harsh shifting along with codes being set. One is for the solenoid if it gets clogged. Another is for bad connections at the 20 pin connector going to the transmission.