Hello need help! Problems with trans shifting hard on 2008 Edge SEL AWD

[RL256]

Hi, i bought a used 2008 Edge SEL AWD in January. It had 45k miles. at about 55k, it started shifting really hard, mostly on the interstate at hwy speeds. it has done it at low speeds also. It seems to do it more often after driving 40+ miles a day. I have taken it to 2 different dealers. Of course they couldnt reproduce the problem. One of them did reflash the PCU, but the next day, it shifted hard again. took it to another dealer, they kept it for 2 days and couldnt find a problem. also, if im on an incline, the edge will roll back pretty far kind of like driving a manual trans. autos shouldnt do this, right? if its in park, it has a lot of play. I can push it backwards. If never seen that either. should i take into the dealer for that? would they even consider that a problem? I have about 57k on it now, and am afraid I would have this fixed before the warranty expires. any advice?

 

thanks

Ryan