04.4 3500 DRW no mods...Up to my eyeballs with a job we took on,so might be a day or two before I can respond..read and re read posts about surging on return to idle.Mine will surge(not smooth) after rev and on way back to idle.Post show some have had issue since new.After reading the FCA is inactive for aprox 35 seconds after initial startup,I revved mine up after about 20 seconds of running.No surge and smooth return to idle (one post I wish I never read,I didnt even notice mine doing it till read it on here.Now going to be **** about it)After about 1 minute running time,it will surge again on idle return. If I understand this fuel system,it is in open loop(the ECM) for aprox 1 minute after initial startup.This leads me to believe that the surge is coming from something that is out of the ECM info loop(when its cold start and running on pre programmed open loop) or bad programming for the FCA circuit? I may be using bad terminology.I understand open loop to be engine recieves commands from pre programmed fuel maps ect till ECM sees that engine has ran long enough to run on actual sensor data(closed loop) I went to parents and tested their 05,no surge anytime.