i would address the glow plug issues first and see what that does. has the controller ever been replaced?? does it smoke considerably on cold start up and take a while to clear up??
do as mike said, go underneath and reach up to the overflow and see if it is wet. if it is overfilled, it could leak out the overflow up top like mike stated. .
mine does this also. seems to do it when cold and you can feel the abs kick in too. doesn't seem to do it with tow haul on. upshifts and downshifts fine otherwise.