I have a 03 dodge cummins 6 speed manual that I picked up about 2 months ago it was a one owner off a older couple bone stock when I purchased it and still had this problem. It will typically idle at about 1100 rpms but if I let the clutch out in gear and drop the rpm it will idle around 800 tell I give it gas. It will start to accelerate rapidly when I start sometimes and also likes to jump about 300-500 rpm when I shift at higher rpms. I replaced the APPS sensor with a new one and that did not fix it the new sensor is working great and is in specs. Any ideas what else may cause this? Thanks

 

Are you feeling this spike? or is it just on the gauge? 1100 is way to high for idle!

 

You can defiantly feel the spike. Especially when it surges off the line you will barely be on the throttle and it will just take off and continue to give it gas for a moment after you engage the clutch. I am going to check my FCA today and see if that is it but I am lost the truck runs and tows great other than that and gets 22mpg around town.