Thanks, guys for taking the time to reply!

[BTW, I apparently have a European car, which explains why the Vin number sounded odd and doesn't have VIN in front of it. Does the fact that it's greymarket make any difference it how it should be maintained or what can go wrong?]

In reverse order, I'll answer TxBill's question - yes, it appears to have diesel in it. A cup or two was siphoned from the fuel tank and it had a greasy oily look to it (but still largely clear). What came out of the fuel filters when I replaced them was darker - that may not mean anything.

As to Icesailor and his queries:

My ignorance of diesels may be showing, but I'm expecting a chuffing sound from the engine, not a clack and certainly not a metal on metal clacking when I accelerate. [the term is used cautiously because I wouldn't call what the car does acceleration] I'm not expecting any pep, but I don't think the car could hit 30 without sounding like it's going to shatter. The noise and revs seem to cry out for shifting from 1st to second at about 10 miles an hour and the car seems to want to be shifted at 5 mile an hour intervals. I actually end up in 4th at around 20 to 25 miles per hour.

So far, I've changed both fuel filters in the engine compartment (is there one on the fuel tank I need to worry about?), and the airfilter. Tomorrow morning I flush the radiator and put nice orange coolant in and change the oil (using Chevron Delo 400 15w40). A friend has a can of injector cleaners that works by cranking the car while the fuel lines are immersed in the liquid. After those things, I'll try driving the car around the neighborhood. If I can get it running around here at all comfortably, I'll try getting on the highway.

I'm not touching the glo plugs since the car starts quickly.

If the firing order is off, would the engine even try to run?

Sorry for the barrage of questions, but I seem to have jumped into MB dieselhood without even dipping my toes first...