I have 2009 Ram1500 5.7HEMI.
I had transmission rebuilt about 15000 miles ago. Spark plugs were replaced about 15000 as well. Throttle body cleaned very well around 15000mi.

When truck is at operating temperature level I have slight RPMs drop and lights dim when I come to a stop and sometimes the truck stalls at stop.
I checked for vacuum leaks around the engine but all hose lines were in good shape. It just seemed like it was the problem but apparently it is not.
I thought that the spark plugs were bad but I changed them just 15k miles ago so I think they should still be good (Autolite double platinum).
The battery holds charge the alternator seems to work well.
No error codes at all.
Oil change at around 4000mi with Royal Purple 5W-20 and K&N filter HP-2010.

Does anyone know what could be a problem?

 

Can you quantify the "slight RPMs drop?" Does the A/C work without making extra noise? Have you tried monitoring the battery voltage when this drop in engine speed occurs and just after the engine stalls?

-Rod

 

Rod, thanks for your post.

The truck usually runs at 700 RPMS in idle. Slight drop is by 200-300RPM.
A/C works fine no noise, nothing has changed there.

I can't monitor the battery because it only happens on the road. I tried to simulate driving inside the shop today in the morning but it was working just fine. The battery indicator on the dashboard don't move anywhere and stays at its normal position (in the middle).

When I drive, sometimes the RPMs start to fluctuate by about 100 RPMs. I had similar issues when I had old spark plugs and dirty throttle body. But both of them are replaced/cleaned.

 

Throttle position sensor?

 

There is a TPS inside the Throttle Body only can be replaced as whole unit.
Is there a way to somehow test it? The part costs 100 bucks which is not a big deal. Just don't wanna throw money into the truck.

Forgot to mention, the truck has 198K miles. The TB seems like an original unit.

 

I am not as familiar with the newer trucks as I would like...... Really need a service manual for it, for the wiring diagrams to tell the tale.

 

I have read on other forums that some people replaced a torque converter but in my case it very seems like an electronics' issue.
Only when warm...
And when I restart the truck after it stalls I hear a metal flap coming from the engine bay (sitting inside). But when truck sits for like 5 mins it restarts without any noise.

 

If it felt like NOT releasing the clutch on a manual trans vehicle when coming to a stop, I would take a good hard look at the torque converter, and TC clutch..... but, doesn't sound like that is your problem. The 'burble' in engine rpm while driving though...... that sounds a LOT like a TPS issue. Trouble is, I just don't know that much about the drive-by-wire systems on the newer trucks.

 

It does not feel like not releasing the clutch. When I come to a stop (the vehicle is not moving) around after 1-2 second the RPMs drop. I think if it was a clutch the truck would stall immediately when stopped.

I had that fluctuation when I had bag plugs and dirty Throttle body.
And the problem is I live in Estonia and there are no official Dodge dealers here... I will order new TB from Rockauto. Should have it next week and will update on the progress.

Will google how to re-learn the unit.

 

You should be able to view the TPS voltage and linearity through a scan tool with a datastream mode. Even some of the free or inexpensive smart phone apps and a bluetooth dongle may be able to access this parameter. If the linearity looks good, or if you don't have access to the data stream, you could try removing the throttle body and thoroughly cleaning it of carbon, making sure to clean the back side of the throttle plate, any ridge of carbon around the throttle plate, and any passages for the idle air bypass system.

I'm pretty new to Dodge and my Ram so I cannot claim to have done this yet to confirm the accuracy of my comments above, I'm going off of my experience with other makes/models.

-Rod