I just returned from an 800 mile trip through the Ozarks with no problems.
Stopped 10 miles from home for refressments and the Van (84 GL) would not
start. Cranked and cranked, no luck. Rolled it down a 100 yard incline and
it reluctantly fired up. Drove home and the next morning it started, no
problem. Drove a couple of miles, stopped and it would not start.  Coil
spark is strong but white in color, not blue as I thought it should be.
Started up with dense black smoke; pulled the old, worn out plugs and they
are covered with dry, black soot. Replace plugs, wires, rotor and it
started. Drove two miles and  turned if off, would not restart. Fuel pump
is audible and gas smell is strong but will not start. Several hours later
it starts, no problem. Drive a couple of miles and it will not start. I'm
thinking carburator but I'm a shade tree kinda guy and don't know what to
try next. Any ideas would be greatly appreciated. Joe