I have a 1991 Ford 7.3L diesel that starts with no trouble, while warming it up the rpm goes between 500 to 1100 and stalls. After that it is hard to start and will stall out when driving it warm or cold. I've had the injector pump replaced, and it helped but still have the same problem.

See if this link helps:

https://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-hondas-selected-other-vehicles-46563-8.html#post1415281

Fuel filter blocked ?

I have a Ford 250 Diesel and had the same problem. I would be driving and accelerate hard and then let off the gas and the truck would sputter and gray smoke would pour out of the exaust. I changed the 2 fuel filters and all is good now. When you change them, change one and then run the truck and then change the second one. If you change them both at the same time you will drain the line of fuel and it won't start. You should change your filters every 20 to 30k miles.