OK, so about a week ago, it was all of a sudden (literally from one shift to
the next) difficult to shift from third gear into fourth, or third into
second.  All other gears are fine, including downshifting.  

Do the easy stuff first, right?  cleaned & lubed the linkage box just under
the shift lever (it was dry in spots, and the grease that was there was
pretty cruddy).  Didn't seem to be any excessive play in the linkage from
underneath.  Put everything back together, and "dry-shifted" (engine off)
through all the gears several times.  Worked like brand-new; no difficulty at
all shifting through all of the gears.  Cleaned everything up, put the tools
away (whistling happily).  Got in the van for the "victory lap" around the
neighborhood, and found that, while improved, there's still some reluctance
to get from third into fourth (not really _hard_, but it just doesn't feel
right).

Crestfallen, I squeezed back under for a look at the linkage where it enters
the tranny, and the boot that covers that area is torn, but everything looks
clean.

Question - is it possible that the clutch being worn could cause this?  There
are 92K miles on the original clutch, I've been thinking about replacing it
anyway, but it hasn't started slipping or otherwise exhibiting any signs of
failing, although I have to let the pedal almost all of the way out before it
starts engaging (adjustment is fine).

I appreciate any ideas or help anyone may have.

Cliff
'88 Vanagon GL