I have a 2005 dodge ram 4.7L and I’m having a problem, starting the truck when motor is cool or hot it will idle up and down up and down up and down but never putting out a check engine code. The problem started after I got another truck to drive back and forth to work and I let it sit for about four weeks just driving it on the weekend, dose any one have any suggestions?

 

I had the same problem., Mine was the TPS, but you should check the following. Clean the throttle body and check for vaccumn leaks. Also your EGR valve can cause the problem. First thing I would do because it is the easyest is recalibrate the TPS. To do this you
1) turn the ignition to run (not start)
2) wait for all idiot lights to go off except check engine light
3) very slowly push the accelerator all the wayto the floor
4) very slowly let the accelerator pedal all the way back up
5) turn off ignition
6) start engine and see if this has fixed the problem

 

https://dodgeforum.com/forum/3rd-gen...-problems.html

same thread

There are lots of threads on idle issues and can range from TB needs to be cleaned, bad fuel (not good to let ethanol blended fuels sit as it absorbs moisture and separates), EGR maybe clogged, vacuum leaks