My 02 se has been shifting hard on and off,but now its all the time and its a much harsher shift.It does seem fine at highway speeds and has never slipped.Changed the filter and refiled several months ago,with no change.Could this be a simple fix perhaps or a new tranny.Also this has to be hard on tranny and motor mounts I would think,so I dont want to cause anymore damage.
my 2005 does the same it'* called adaptive shift the 4t65 has this its a program to save the tranny when slippage accurs what happens is when the input sensor and output sensor dont comply with each other it ups the trans pressure so that they do and eventually max out the pressure when this happens it feels like the trans should be in a drag car it shifts so hard plug it in to a OBD2 reader and see what the 1-2 3-4 adaptive shifts look like shouldnt see more than 10-15 psi if you do on all shifts its a persure control solenoid i think if its just in one gear then its the clutches let me know what you find
I had the same problem with my 2000 SSEi with the pressure control solenoid (600-700 dollars to have repaired). I installed a shift kit ( Thrasher-medium setting, 3 months ago) to by- pass the Solenoid problem and have not had a hard shift since. $95 for the kit/filter plus new fluid)