2004 5.9L Running Weird

[JohnM]

Hello all, this is my first post here and it has to do with my 2004 RAM 3500.

I've been noticing over the past few weeks that the engine will rev up about 100-150 RPM's when letting off the brake at a stop.

This is pretty alarming since it causes the truck to jump forward a bit more than expected. it also seems to idle odd, with no difference between drive, reverse, or park.

The best I can describe this would be a "lope" but ill attach a short clip with it happening below.

These problems are intermittent, and I'll only notice it happening every other day although it seems to be getting more frequent.

I have noticed a few things I can do to trigger it, but this only works after I first notice it starting to stumble.

In park, If press on the brake and let off, the engine starts the "lope," and after pressing and releasing the accelerator pedal it stops.

The other trigger is if I again, in park, turn the ac on full blast, wait a few seconds, and then shut it off.

I will say that these are not the only things that cause it, as it will sometimes just randomly start the "lope," but they do seem to aggravate the issue.

I should also mention that the RPM's don't come down smoothly if in neutral and brought up to 2000 RPM.

I wouldn't say they hang but will be a bit choppy although I don't know if this is normal as I haven't had anything to compare it to.

The truck has 175,000 miles on it but I'm not sure of Mattiace before about 140,000 miles which is when I bought it.

I've replaced the fuel filter every second oil change, with oil changes every 3500-4000 miles.

I ran Diesel Kleen in it for a couple of months but stopped to see if the problem worsened without the additive.

I haven't noticed a difference.

Cold and hot starts are the same and I don't notice a difference there either.

Any ideas as to the potential causes would be greatly appreciated.

https://drive.google.com/file/d/1-ii...fHOWGOYZI/view

Unfortunately, the transfer from my phone to the computer caused the audio in the video to get muffled, so the engine is harder to hear.

You can still notice it, but not quite as dramatically as in person.

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[JohnM]

I would like to add something I noticed just in case it its of any use. If I bring the RPM's up to 1000 in park, the truck starts to shake quite a lot. Any higher or lower and everything smooths out.

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[AnOldBiker]

to the forum @JohnM

I haven't heard of anything like this before, and after seeing the video, its hard to see it.

Someone should come by soon who might know what it is and what to do of it.

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