Diesel Bombers - 7.3 p1280 code.

Hello everyone, I have a 99 F250 4 door superduty7.3 she has 330,000 miles on her I just replaced cps. She runs but now she throws a hard and constant p1280. My ? What should I be looking for to diagnose this issue my concern is I don't want to throw new and good parts on a tired engine. We all know injectors and HPOP are not cheep. I'm am not sure of the age of the injectors they have numbers on them like they were taken out at one time. I bought the truck with 130,000 her and really haven't done much to her I don't want to get rid of her I love this truck she has been the best vehicle I have ever owned. I have an autoengienuity PC scanner. Its been pretty cold out she's too tall for my garage so my work is done out side. Any help pointing me in the right direction would be awesome. Thanks in advance. And Happy New Year to all.😕