Employing Mori-formalism we calculate the polaron transport of an exciton-phonon system; with linear site-occupational coupling. The main feature of our approach is a consistent treatment of the memory function, which is of 2nd order in an effective "smallness parameter" appearing after a Lang-Firsov transformation has been made. The memory function is divided into a quasicoherent part, which can be interpreted as a band type motion, decreasing with increasing temperature, an incoherent part describing usual hopping dynamics and two crossterms. In contrast to previous similar approaches our results do not display any divergence problem. It is found that the two cross terms yield a small transport contribution of coherent nature, at least within the accuracy of the present approximation. Due to this term, although higher order effects may result in a damping, the transport will display coherent features for a long time.