I have an 04.5 cummins that is stock except for a 4” exhaust. It started cutting out really bad. It will cut out for several seconds at a time. There are no codes. I changed the tps sensor, injectors, *the sensor on the back of the injection pump and the fuel rail pressure thing. Just to see what would happen I took the smarty s06 tuner off my other truck and installed a tune on it and the problem went away except it started surging when it gets up to speed. Not bad but you can definitely feel it. I’m at my wits end and am losing my mind trying to figure it out. Any help would be most appreciated.

At the pump 17 at an idle and 12 getting on it. At the rail 6,600 idle up to 22,000. I’ve checked all the easy grounds.

What I don’t get is what is messed up that doesn’t throw a code and the smarty s06 changes

It runs perfectly when it’s cold to.

After some more trouble shooting I found out it’s turning the shift limiter off on the smarty that is fixing the problem. Any ideas?