starting problems

[Lhthomas300D]

'85, 300D turbo diesel (straight 5) recently conked out and won't start. Car started sounding flooded or not enough gas going down the road and then eventually cut off and it won't start back up. (even with battery cables). Doesn't seem like it would have anything to do with the
G plugs since it conked out while driving. Everything turns but it won't crank up, just keeps acting like it wants to start but won't catch. Replaced both fuel filters to no avail, could be the fuel pump I suppose, but don't know their reliability. I'm at a loss being a new diesel owner (and don't know too much about diesels anyway), will gladly take any input. Thanks.