2001 seville sts starts in 2nd gear
 

the transmission has 149,000 miles & needed an overhaul. after the overhaul, it worked perfect for about 2 months & after parking one evening, i went back to it the next morning & it would not move in forward or reverse. my transmission shop went back into it under warranty & found "something broken"(not sure what) inside & when repaired this time, it starts in 2nd & as soon as you give it a little gas, downshifts into 1st gear. i even think reverse feels like it might not be starting in the lowest possible gear. maybe this part is my imagination because i know there is only one reverse gear. they tried replacing the valve body, but it made no difference. no codes are coming up. any ideas?

too many possibilities a seeping seal or check ball in a drum that seals with a slight increase in line pressure is a guess. Unfortunately trans has to come out and be disassembled to check.