When I open my powered hatchback of my 2005 Toyota Sienna on cold mornings, it power raises, but will often then power lower. In a way it seems like it has "hit" something at the top of its raising cycle, but there is absolutely nothing above it. It happens whether I open it using the handle, the button in the car, or the remote. It seems to only happen when it is cold. Is there anything this can be other than the struts?