Was having some stumbling problems with my '84 GL when it would get low on
fuel.  Also leaked gas when I filled it all the way up.  Found a leaky hose
between the fuel tank and one of those two plastic expansion tanks in the
wheel wells.  After replacing the line both the leak problem and the stumbling
when low on fuel problem were solved.  Check these lines and the tee fittings
on top of the tank.  Also the rubber grommets that seal the tee-fittings to
the tank.
Ken Wilford
John 3:16