I would replace the fuel filters. Check to see if the fuel lines are leaking, granted you would have to be lossing a lot of fuel to loose that many miles, but it wouldn't hurt to check. Although with a 92 I don't think the hoses will be a problem, but I am not sure exactly MB changed from the old rubber hoses.

How many gallons of BD has been put through it?
Did the driving change at all? From all highway to all city or something similar?

__________________