Power surges 96 2500

I have a 96 2500 with the 5.7 and 5 spd. From idle to about 2k rpm I have no issues. From 2k to about 3500 rpm it spits and sputters and I'm lucky to get it any higher than that. I just did the fuel pump because it wouldn't even get above idle and it seemed like the culprit. Well the fuel pump seemed to help a little. Like in getting more fuel pressure than I was but still not enough. I know test the pressure blah blah blah. I work way too much to trial and error this thing. I have about 15 minutes a day with a burger in my hand to put parts on and that's it. I won't have more time till fall when farming slows down. Seeing as the fuel pump and filter are both new, my next thoughts go to the fuel pressure regulator or whatever the spider injector thing people seem to always mention. Any thoughts? I'd like to stay as cheap as I can but would like to just get it done as diesel is getting expensive again and I'm not supposed to use my gas card for diesel. I don't know what other things might be cutting my issue... I did put injector cleaner in it. Figured it cant hurt with 235k miles, all farm and dirt road driving.

You're too busy to do proper diagnosis, but you've got time to take wild guesses and throw parts at it?

You're too busy to do proper diagnosis, but you've got time to take wild guesses and throw parts at it?
Seconded!