There is however a technical service bulletin for this problem and here it is:
Engine Controls - Poor Idle Quality NUMBER: 18-038-08
GROUP: Vehicle Performance
DATE: October22, 2008
THE StarSCAN(R) FLASH FILES FOR THIS BULLETIN MUST BE RETRIEVED FROM THE INTERNET.
StarSCAN(R) SOFTWARE LEVEL MUST BE AT RELEASE 9.03 OR HIGHER FOR THIS BULLETIN.
StarMOBILE STANDALONE MODE OR StarMOBILE DESKTOP CLIENT MAY ALSO BE USED TO PERFORM THIS PROCEDURE.
Flash: Idle Quality Improvements
This bulletin involves selectively erasing and reprogramming the Powertrain Control Module (PCM) with new software.
2009 (DS) Ram 1500 Truck
: This bulletin applies to two wheel drive (4x2) models equipped with a 5.7L engine (sales code EZD) built before October 3, 2008 (MDH 1003XX).
Some customers may complain of the idle quaility after the vehicle is warmed up. This condition can happen while the vehicle is in park, neutral, drive or reverse with no additional throttle tip in. A software change has been made to the increase the warm nominal idle speed from 584 rpm to 648 rpm, which corrects the condition.
If the vehicle owner complains of this issue reprogram the PCM with the new software.
Using a Scan Tool (StarSCAN(R)) with the appropriate Diagnostic Procedures available in TechCONNECT, verify all engine systems are functioning as designed. If DTC's are present record them on the repair order and repair as necessary before proceeding further with this bulletin.
SPECIAL TOOLS / EQUIPMENT REQUIRED:
REPAIR PROCEDURE - USING THE INTERNET TO RETRIEVE THE FLASH FILE:
1.Reprogram the PCM with the latest software. Follow the detailed service procedures available in DeaIerCONNECT/TECHCONNECT, Refer To 8 - Electrical/Electronic Control Modules/Powertrain Control Module - Standard Procedure PCM/ECM Programming - Gas.
2.Type the necessary information on the "Authorized Modification Label" p/n 04275086AB and attach it near the VECI label.
Reimbursable within the provisions of the warranty.
So it looks like if you mention it to the dealer they should correct it! hope this helps!