I just bought my 05, 5.4L,FX4 (W/35" tires) with 75,000 miles, It shifts good, kinda softer then I prefer, but no slipping felt. But often after sitting at an idle in gear, there is a "Bump" felt upon giving it the throttle, it dosent feel like slack to me, I can even ease ever so slightly on the throttle and start moving foward and then throttle up and feel it. Does this sound like a trans problem? Also in a couple of weeks Im going to drop the trans pan and change filter and fluid, any recomendations for any modifications that might easly be done while Im in there short of rebuilding? Any advice?