2001 Didge Ran 1500 – Misfire?

Greeting’s all I got a 2001 Dodge Ram 1500. It now has about 164k miles on her. Its the 5.9l gas v8, 4×4, auto trans. I acquired her this past summer. Love my truck despite her little issues. I do have one thats throwing me a bit tho. I’ve noticed on long drives that put me on the interstate (more than an hour drive time out) if Im climbing a steady hill (such as the ones on I-71 by Ashland or proceeding north of there) I’ll get what feels like a misfire. It only occurs on a hill with a steady but long duration grade if that makes sense. If Im holding normal speed and about 2k RPM I’ll get a vibration it almost feels like Im going over a rough road at first and then I feel a slight bucking sensation and hear a bit of a popping or a back fire. If I shut off cruise and completely come off the gas the misfire goes away. Sometimes if I shut off cruise and go to WOT it’ll go away too but not all the time. When all of this is going on I’ve seen the check engine light flash (misfire code) the last time it did this when I got it home there were no codes in the computer. I guess the condition wasn’t going on long enough for the computer to confirm the code.

This problem has only come up if I’m on longer than normal trips specificly going on the hills at interstate speeds. I dont do these trips too often. And the truck never does this on my daily or weekly trips although it should be noted my daily/weekly trips are much shorter and with no interstate travel.

I was wondering if y’all might have any suggestions.

In recent months I’ve done a tune up on the truck (wire’s, plugs), bleed the cooling system, oil change back at 160k and my owner’s manual says Im good till 167500, and a transmisssion fluid change at about 163k. The power steering pump had to be replaced recently and it was only after this that the issue first arose although I dont recall very long trips with the truck before the power steering pump change.