Can't speak much for where to find a 91 but I have experience with my 87 
automatic that you should know about.  I think that the automatic 
transmission is as reliable (if not more) than the standard since it is 
pretty hard to screw up the shifting and grind gears, ride the klutch, 
etc.  I unfortunately sprung a leak in my transmission oil pan, ran it 
out of fluid, and had to do a $800 transmission rebuild.  I don't think 
it is alot more than a standard would cost to rebuild though.

The part that really sucks is the lack of a fourth gear.  Redline in 
second is under 55mph making it tuff to do more than 50 or so up any 
hill.  With the standard you can easily do 60 in 3rd with another gear 
to go!  I lived in Colorado and did alot of mountain passes in it.

When I get another van (I too will be looking for a 91) it will NOT have 
an automatic transmission.  I would not encourage anyone to get one 
either.

Chet
-- 
Chet Douglas - CRD Consulting - Peripheral FW,SW,and Drivers
(541) 754 - 1817