MOST LIKELY CAUSE IS VALVE BODY. THE BORE OF THE PRESSURE REGULATOR VALVE GETS WORN, THIS CAUSES SOME DELAY AND A KICK WHEN COASTING ON AN UPSHIFT, SPECIFICALLY FROM 3RD TO 4TH. SOMETIMES OTHER HYDRAULIC CIRCUITS ARE AFFECTED AND SIMILAR SYMPTOMS OCCUR ON DOWNSHIFTS. TO TRULY FIX THIS PROBLEM YOU MUST REPLACE THE VALVE BODY OR FIX THE BORE AND REPLACE THE REGULATOR VALVE WITH A LARGER ONE. THE REPROGRAMMING SOLUTION IS A MASKING FIX. IT SOLVES THE PROBLEM BY INCREASING THE HYDRAULIC PRESSURE TO COMPENSATE FOR THE LOSS OF PRESSURE LEAK CAUSED BY THE ENLARGED BORE.