Any guesses on this?
 

Drove my 1990 w250 to a neighboring town...shut it off. Started up about an hour later ...fired right up but you could could only give it about 1/3 throttle before it would cut out...sounded exactly like a rev limiter on a modern gas motor. No smoke of any kind or any telltale exhaust clues. Since its a manual I kept the revs down and drove it home. By the time I got it back home, about 25 miles it was (and is) running fine. Lift pump? Imminent injector pump failure? I have never had a diesel do this before except my dying VP44 in my old 2002 so any suggestions would be appreciated. Thanks.

Fuel filter plugging up? Or could be a bad lift pump too? Sounds to me like the injection pump was not able to get enough fuel.

I thought more the lift pump cause I didnt know if a fuel filter could "unclog" itself but I wasnt really sure. Truck has 102k miles but original lift and injector pump.

Filters cannot unplug themselves. That is good thing, as if they did unplug themselves, think of the damage that could be caused to the IP and the injectors...

I would replace the fuel first. My old MB uses two filters, and when they get clogged (from lack of changing on time), the same thing happens like what you are experiencing.

Fuel shut off wire loose/loosing connection?

I did replace the FSS several months ago so I will recheck the connection and rrgrassi I too have an MB 300D (an 85) and have had that problem. It sat for so long before I bought it i would be afraid to look in the tank. I just put biocide in it and am ready to change the filters on it and I guess the truck too. I guess a person just cant have too many 25 year old diesels to work on.[duhhh]

I would change out the fuel filter first, once I get the old one off I like to empty it out in clean bucket, kinda gives you and Idea what your fuel is looking like.

It's a fairly good idea to change over to a ring terminal rather than the spade terminal it has now. You seem handy enough to not need a set by step.

I should have done that when I changed it. Spade clips are for speakers.