Yikes! Sounds like quite a list of woes. However, here are some points to consider:
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1) As someone has pointed out, the big repairs have already been done and you have spent a lot of money getting them done.
2) $4000.00 represents, what, about 1 year's worth of payments?
3) As someone else has pointed out, the big depreciation has already happened and you are practically guaranteed between $2,000 and $4,000 on a sale.
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In conclusion, I would run it for another year to get your money's worth out of the repairs and to pay off the remaining 4K. Then sell it or trade it with no debt owing.
Also, the maintenance that articsteve recommended sounds like just the ticket to keep you moving. As for what to buy, ask yourself if you still need a van or can downsize. If you do need the space, consider Toyota, Honda and yes even the new Kia van or its soon to be released Hyundai brother (2007)