Shuddering & voltage issue

[Six0Denali]

Recently my 2006 Sierra 6.0 started having a odd issue. Voltage is moving around erratically but the truck is shuddering as well and rpm fluctuating a few hundred rpm when shuddering almost like when a manual trans vehicle is about to stall out. Battery and alternator are good as well as voltage regulator. Not sure what could be causing a shudder with voltage fluctuation. Any help would be appreciated !  
 

note only mods are intake, and long tube headers. Nothing done internal and no aftermarket electrical accessories. 

[davester]

So, you had the alternator and battery off the vehicle and tested to verify they work correctly?

 

And is the voltage actually dropping (as in, you used a voltmeter to test that the voltage is dropping when the engine shudders)?

 

Anyway, you need to figure out if the voltage dropping is causing the shuddering, or if the shuddering causes the voltage to drop (ie, engine slowing down will cause the alternator to not put out enough power).

[Korbin]

I replied on your other post about this but it’s probably a ground is moving while your driving