Check the condition of the suction side fuel line -- if it has gone bad, you will have both fuel starvation and air in the fuel system. Lack of power and hard starts are typical.

Check ease of rotation of engine, too -- if it is very difficult to turn with a socket on the damper bolt, the bearings are bad.

And re-check that oil -- if it has a cracked head or bad head gasket, you may be getting water in the oil, with siezed bearings possible.

However, bad or spun bearings usually knock something fierce, or squeak when cranking.

A slow starter is a distinct possibility, too, but I'd bet on the bad fuel line -- this happened to me on my 220D and to my brother's 300D -- stalling at speed and very long drawn out starts that ran the battery down, couldn't get the fuel system primed with the hand pump. New fuel line fixed it right up.

Temp guage is electric on this car, oil pressure guage is mechanical -- check for loose wire or kinked oil line.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!