I have an 01- 5.9 cummins,bone stock.This started about 6 weeks ago.
At idle the motor will go from 800 rpm's down to 100-200 rpm's and almost shut down.
It will do this for about 3-5 minutes off&on.The engine light then comes on.All of a sudden the motor stops doing this and runs fine for a while and the engine light goes out.We checked for codes while it was doing this and none showed up.The fuel filter has been changed again.The other fuel filter was about a month old.When the motor comes out of it the truck runs fine for a week or so and then does it again.I am not a diesel mechanic at all.It's very cold up here in Maine.I thought may be bad fuel but i always use a conditioner(diesel cleen) whenever i fuel up. Thanks in advance.

 

Could try howes but it sounds more like a sensor. I don't know if these are as reliant on sensors as a gas engine but I think they have a crank sensor which someone else can chime in and tell me if I am wrong or not?