1997 Z28 Automatic Hard shifting !

4l60e Trans has code po753 shifts hard but no slipping. Trans make noise at idle , but when you clear the code it stops. The Check engine light comes back on, The noise in trans starts again. Ive read the computer command the trans to full line pressure. Trans fluid looks ok not burned . Trans was rebuild about 5 years ago, Any input would be nice.... Update on problem New trans filter , 12 Quarts Of fluid , Flush system 2 New shift solenoids , Cleared the codes shifts smooth....