My truck surges at idle and part throttle every so often. It will jump about 100rpm and then settle back down and be fine for about 3-4 secs, then do it again. I don't notice it at highway speeds, but driving around town and sitting at a stoplight it will do it. Only does it when in gear, forward or reverse, and only at zero to light throttle. The ijectors were replaced 8000miles ago by the previous owner. Also it happens in all states of tune with the Banks.