Silverado 1999 Z71 Transimission

I own a 1999 Z71 Chevy Silverado (old body style) i had the transmission re-built about a year ago since then i've put 30k miles on my truck. Well my transmission is acting up again. The problem i'm having is the transmission is slipping when i'm slowing down for a turn then i give it gas so it feels like it does it between 1st and 2nd gear. It's not as noticeable at a dead stop and then you accerlerate. Any ideas? Last year the problem it had, was the hard shifting from 1st to 2nd, which ended being the valve body.