thier was a problem with the injector wiring harness on those trucks don't remeber the exact problem but would make it run like crap....

 

The injector wiring issue is the "ice pick fix" o ijectors 2 and 7 but that almost always throws a code when it happens.
Have him check the wire loom that is zip tied to the altenator bracket. The bracket will rub through the insulation on the wires and cause them to ground out.
How to fix is cut the zip tie. Open up ant inspect the wire loom for any broken wires. If any are found repair them if broken, then re wrap the loom with electrical tape. Next take a piece of heater hose and split it. Put it between the wires and the altenator bracket, then re zip tie them to the altenator bracket.

 

I would do the following

1) Ice pick fix on all injectors
2) Reinsulate FICM harness at alternator
3) Use full 32oz of Diesel Kleen in a full tank
4) Recheck your balance rates (may have a bad injector or other issues)

 

He ended up putting a bottle of Lucas diesel treatment and it straightens it up. So it's back to normal now.

 

Sounds like he got a touch of bad fuel.. happened to me with similar results