i have 2006 GS300 have 86,000 miles and i have same problem shifting and doesnt have pickup and the check engine lights is on, i went to the Discountautoparts and they checked it for free and gave me the error code:
it was "P2757 Torque Converter Clutch Pressure Control
Solenoid Control Circuit Performance or Stuck Off ".
i just ordered the soleniod from lexus and tans seal and fuild they cost me $192.00
tomorrow i am gonna get the parts and i will take to my friend he machanic i hope he can fix that
and yeah! when i went to Lexus Service Dept if they can change the solenoid , they told me they cant fix anything inside the trans, they have to change trans and it Cost $4000.