Ok, I've got a 2002 1500 crew cab long bed with the 5.9 Magnum. 2wd. It just turned over 200k miles. My issue here I've read before but no one had a video or really even a fix so I figured I'd make my own post.
Problem: when traveling at highway speeds around 60ish mph, the rpms jump about 100 rpms continuously. Abput 1800-1900 then back down to 1800 then to 1900 and so on. You can hear it, and see it on the gauge. I've had the truck for a few years now. Previous owner did a rebuild on the tranny at about 160k. But its been going for the better part of a few months now.
I've replaced the TPS, done a new intake (k&n), made sure cables were good, sea foamed the throttle body and intake, made sure spark plugs and distributor were good, did a deep clean on the injectors. Idk what else to do. I've read that running a ground line from the throttle body helped the 3rd gen 5.7s. But I haven't seen anything about that for the magnums. Nor do I know how to go about that. I have a video too if I can upload it from last night. Anyone else having this issue with the magnum engine and if so, did you fix it?? Thanks guys!
update, cannot upload the video. Hopefully yall know what I'm talking about.

 

A fair few of the third gens are throttle by wire, so, running a ground wire for them actually helps. Won't do anything for you.

Still sounds like you have a TPS problem though. Might wanna test your new one with an analog meter. Not like I have never seen bad parts, right out of the box.

 

So it started a few months ago, which is why I replaced the TPS. It dulled it down but never went away.

 

What brand TPS?

 

If I remember correctly, it was a car quest premium from advance auto

 

HHHmmmm...... I might be tempted to swap it out with a Standard Motor products unit, or a genuine mopar sensor..... When my truck was doing that, changed the TPS, problem went away.

 

Where did you pick yours up/order yours from?

 

I went to my local Advance Auto Parts store. Been dealing with them for decades, and we are all on a first-name basis there.

 

They have a Dorman OE but thats the only OE they have. I would assume thats fine.

 

No. Dorman sucks, especially for electrical parts. Get one from the dealer, or order one online then. They cost more, but, they actually work right.