what is causing my idling issue?

Intake manifold internal leaks? Run the test for it. Fuel trim problems? Run fuel pressure and flow tests. Canister purge trouble? Run a system smoke test.

Unfortunately it has been to the dealer and several other shops and no one seems to be able to solve the problem.

I will be running a fuel pressure test and running a smoke test for the evap system. I checked the intake manifold for external leaks and I found none. Would could be leaking internally?

Yes it could.

What would possibly be leaking internally?

Lower intake gaskets, manifold to head gaskets, some of these had a plate that was attached to the very bottom of the air chamber and that plate also can leak.

I had replaced the intake manifold gaskets when I took the manifold off when I did the mds delete of the truck. I also checked the TB bolts and intake manifold bolts and they were still all torque to the proper spec.

I would still run the pressure/vacuum testing on the intake. Something is causing the fuel trim condition on the live data scan.

Thank you so much for your help will update along the diag process.

Update: took a closer look at the voltage values of the oxygen sensors. B1S2's voltage was all over the place while B2S2's was steady as it should. I also verified the purge solienoid works and is fine. Tested for vacuum leaks at the manifold and there was none. Tested the evap system and it has an evap leak from the canister esim assembly. I believe I have finally solved the problem or at least the cause of the rough idle condition. However I'm still puzzled as to why it never threw any codes at all over the last couple years?

So either a catalyst problem or an O2 sensor is bad. make sure the sensor grounds are good. A leak from the canister can cause a lean condition as well as a rich one.

ECM protocols probably over rode the check engine light cause it was so intermittent

Do you know why it would not set any trouble codes for these conditions?

Will update when I change the sensor probably won't be for a few days as I won't need to drive the truck for a while. But thanks for your help.

OBD 2 ECM’s have some redundant features that can make diagnosing some problem difficult. That’s why live data is so vital when trying to track down problems that the computer just will not acknowledge. I remember a number of years back a customer was having a stumble on acceleration but it wouldn’t always do it, and no check engine light ever came on, he had been to several shops and no one could find the problem, so it was my turn, he dropped it off and I hooked up my scanner and started driving it, at first nothing, then one morning it happened and the scanner grabbed it, the TPS showed a complete open just for a split second but too fast for the ECM to even see it. Replaced the sensor and had a happy and repeat customer.

Not posting again

Problems Solved! I did not end up changing the O2 sensor instead I did some more digging and turns out it was all from the battery. The battery was from 2017 I tested it several times and it came up good every time. But I read some forums about Ram 1500 acting weird with old batteries. Bingo fixed all the problems and drives better than new. Thank you for all your help and input and if anyone has a Ram 1500 with an old battery even if the test come back good... CHANGE IT!

I’ve never heard that one before. I wonder if a lab scope would have been able to pickup a feedback.

I know it's pretty weird. Never would have guessed it either. But I'm happy it's fixed!