after 8500 miles of 19.5  to 21.5 gas mileage... my van has learned a new
trick... the mileage is now down to between 7.25 and 9.5 miles per gallon...
I have been under the van and all over the engine compartment and can find
no evidence of a leak... though I cannot think of what else would cause such
a drop in mileage without a drop in performance... the van is running fine
... no black exhaust smoke ... and  plenty of power.. I have scheduled some
lift time for early next week to do further leak checks...

I would appreciate any insights and suggestions...