I've never found the FI components of a vanagon to be a source of
on-the-road problems.  Cooling system components are another story,
however.  There are so many formed hoses (all quite expensive-$30-50 each)
that carrying spare hoses becomes an intractable problem of "which ones?" 
I carry a hose repair kit from my FLAPS with various size clamps and
plastic connectors which will hopefully allow me to make a temporary repair
with help from generic hoses available at roadside places.  I do always
carry a spare water pump in the van, having had one go once in the boonies
2500 miles from home.

I also carry a fix-a-flat canister and a tire pump, spare fuses, jug of
phosphate-free coolant, funnel, and tools.  I'd also recommend a LiMBO
membership so that you'll get their traveler's directory (a list of people
nationwide who are willing to help out VW busers in trouble).  Possibly the
best thing to carry with you is The Bus Depot's phone number-610-754-VWVW. 
Ron can get almost any bus part to you anywhere in the country in short
order.  If you have a portable PC that will allow you to access the list
while traveling, that would be a huge help-the hundreds of helpful people
on the list have bailed me out of many a jam.

Bill