I had to isolate my apps wires from the main wiring harness to keep it from doing that , my truck is also a 2002 cummins
Locate the APPS wires
Seperate the Group of wires that are twisted together ...thats the apps Single going to the ECM ,,, it getting interferace from the other wires in the Split loom ...
Here it is pulled out of the Loom Below the ECM ,,
Note Remove Air Intake Manifold and Fuel Filter Housing for access
Here they are going into the ECM connection
Just Pull this set of wires away from the other and run them in a separate split loom ,,,,then poak all the other wires back in the OEM split loom and put it all back together
Good Luck and if your still having trouble Call 1-740-743-2100 ask for Brian and tell him whats going on
DM -