I have a 94 Z28 with an automatic transmission and everytime i take her out for a drive after shes been sitting around for a couple hours i get a hard/some what hesitant shift from 1st to 2nd, but then after i drive it around for about fiteen minutes it goes away what could be the problem?

thanks in advance for the help it is much appreciated

 

what color is the fluid

 

It still is reddish brown