I've had the same trouble with the back door. Take off the inside door panel and you will find a grayish foam liner glued to the door. At the bottom of the liner, if you look up from underneath, you will see that there is a gap in the "glue" or whatever it is attaching it to the door. You could try to get some rubber cement type of sealer (form-a-gasket or something like it) in there to complete the seal. I've got to redo mine. Must have done a crappy job the first time! (hey, it was cold!)
