Alright so new batteries and the alternator tests fine grid heater is unhooked. Doesnt happen all the time just sometimes when driving and idling. On my edge insight cts2 it will bounce between 13-14 volts really quickly causing the engine to lope and dash lights to flicker between bright and dim really quickly. But if i turn my blower motor up on my ac it will eventually balance out and be fine but will come back after awhile. Any ideas? I checked all power cables and grounds.

truck is a 2009 6.7 deleted and tuned with efi live by HPP

 

Mine is doing the exact same thing and I'm still trying to track down why it's doing that... If I find out what it is I'll most certainly let you know.