P pump problem?

[jg95]

For my 95 Ram 2500 Cummins, 250k miles-

Problem only occurs on long drives on highway in hot weather. After a few hours, loses power and feels like it is misfiring. Have to pull over. I pop the hood and let it cool 1/2 hour, it's fine, until I drive it another hour, heats up again, same problem.

Mechanic says its the P pump starting to die. He says $2500 for a good rebuild, says he won't use the cheaper rebuilds.

Is this what they cost these days?

Sound like an injection pump problem?

Lifter pump was replaced a year ago.

Thanks

Jeff G