2007 8.1 hunting

I have a 2007 Crusader 8.1. The motor starts to hunt at about 900-1000 rpm after reaching operation temperature. And then loads up and stalls. Anything below 900rpm and above 1000 rpm it's fine. I used a scan tool and no codes are coming up. Any help would be appreciated.

most ECU's only turn on the light (set a DTC) when a sensor is 'bad' where bad means out of range....the delphi example is an ECT that is ~ 50 degrees off but still in a "legitimate" range. so you need to verify the sensors' outputs with the scan tool....

The other thing is that the ECU doesn't monitor everything, and the list of what it does check varies with the ECU/model year - newer ones do more than older ones....so a problem may occur w/o and DTC....

I'd be inclined to start by removing the IAC unit and cleaning it.....10 years of time would be a decent service interval....

turns out there's no IAC on that engine.....suggest you do a www search on "crusader" and "ECM-07" you should find a pdf file that will explain most of the controls used....there are several areas that cover 'surging' idle....