well i recently had my trans put in the sonnax valve kit because it was shifting REALLY HARD from 1st to 2nd when the trans warmed up....so after it was put in i started gradually noticing that my trans was shifting hard again from 1st to 2nd but it did it every time not just sometimz is this a problem the gus at the shop said the valve kit would fix it for good. but it still shifts hard and i dont haver the money for a new trans......

 

check your throtal positioning sensor. i had one go bad in my truck and it shifted really hard from 1st to 2nd and the other gears shifted slightly harder then normal but nothing like the 1st to 2nd shift