'04 1st to 2nd clunk

Hi, I've read this thread here before but I cant find it now. My '04 silv makes a clunk when shifting from 1st to 2nd gear. It only does this under slow to normal acceleration. If I give it a lot of gas it shifts just fine. Someone mentioned bringing it to the dealer and reprogramming the tranny computer...I was wondering if anyone has done this and if it worked or not, Thanks a lot