Codes

Did you check the voltage with the truck running?
Maybe the Alternator is overcharging.

 

Check all your grounds.

 

I'm already done

 

Done and the problem still exists

 

Did you check the grounds at the ecm plugs?

 

Probably got a damaged wiring harness somewhere.

 

That's what I'm thinking. I had one that gave us fits, ran great when it was at the dealer but when it was under a load, it ran like crap, the next mechanic pulled the connector off and checker the power ans grounds it was a ground that caused the problem.