Our 07 Expedition EB EL has the exact same problem. Your description is identical to the way our's is behaving. It will not downshift to first gear unless you come to a 100% dead stop. We get the same "jerk" as you describe if you come to a rolling stop then accellerate. I had an F250 owner tell me that the 250's do the same thing.and that that's normal for a heavy duty transmission. I'm not so sure about that but it's very annoying. Otherwise we love it. It's our third expedition. I haven't taken it in yet but plan on it. I just hope I don't get the dreaded "normal for this vehicle" or "unable to duplicate problem" run around.