I have a 04 1/2 5.9. Does anyone have an idea why it feels like it is surging except when its on cruise control. On cruise its smooth as can be, but off cruise, it constantly feels like its starving for fuel. I guess its actually the opposite of a surge.

 

Brad,
What modifications do you have done to your truck? Any aftermarket gauges, such as fuel pressure or rail pressure?

 

The truck is stock, there are no mods.

 

If I had to guess I'd say the Throttle position sensor. Try a Timbos on there.

 

by chance do U still have the lift pump on the filter housing, or was the in tank mod. done. Just a idea, when my APPS went out it was about a week after the lift pump went south, my thought was what now and what is next, but reading the codes I determined it was the APPS, order and installed Apps from Timbo's, problem solved, is your Apps by the intake manifold or under the fender {drivers side} if under fender I don't think Timbo's will work hope it helps ;;

 

I had similar issues. It turned out to be a sticking fuel control actuator(FCA). A quart of Supertec synthetic 2-stroke fixed it in a few miles. Add and then fill tank.
No issues since. Cheap fix in my case.