It is a little late now that you have bought the van but I have a '99 Estate that had two fuel injectors go bad (@51k miles) so the mechanic replaced all six (not a cheap repair) at the time (2 yrs ago), I had read several internet forums that this was common for my vintage Estate. I hope that was remedied in the '00 models.
The other thing to check is your front ball joints. When worn, they can really chew through a tire in a rapid pace.