the old girl has 225,000 on her and new filters.

the first problem is prolonged dieseling after key is off, second,she might need to be primed when started after this happens, third after she is below a half a tank[ usually], she will lose power and the pedal will have to be pumped vigorsley to get her going. she dosent stall,its like she just isent getting fuel, any help would be apreciated to keep me from buying exspensive parts i do not need. thanks

When you say new filters, do you also mean that you cleaned/ changed the one in the fuel tank as well? It's on the bottem with the main fuel feed going to it and is a very large nut that you nust remove and then get diesel fuel all over yourself. The vast majority of our diesels, if never having had been done, desperately need this filter cleaned as well. It sounds like one of your problmes is from this.
Good luck, Adam

Could be a bad shut-off valve and/or leaks between the vacuum source and the shut-off valve including the shut-off switch behind the key cylinder.

That won't address hard starting or loss of power. For those things, I'll check the fuel pump (how?) and the primer pump. My SD ran poorly when the plunger of the primer pump backed out. There's a revised primer pump available when the old one fails.

Sixto
95 S420
87 300SDL

The hard-to-start condition could be due to a fuel tank venting problem. When this condition manifests itself, remove the fuel cap to see if the situation improves. If it does, a blocked fuel vent is likely the culprit.

The slow shutdown is likely due to vacuum issues. Try applying vacuum directly to the shut down module on the back of the injector pump. This will rule the shut down module in or out.