Your EGR system is also vacuum operated, so you've covered more than one code. I think your others are injection pump related. Others who are more up on them will probably chime in. I'd suggest you try a heavy dose of a good fuel treatment for starters. Also, the '94 pumps were originally quite problematic, so you want to be sure yours has all the available updates installed.
Should you end up needing a pump overhaul, you might want to look into converting from the electronic pump to a mechanical one, assuming your government would allow that.
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Current oil burners: MB GLK250 BlueTEC, John Deere X758
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Gone but not forgotten: '87 F350 7.3, '93 C2500 6.5, '95 K2500 6.5, '06 K2500HD 6.6, '90 MB 350SDL, Kubota 7510