Sudden power loss

[CGathings]

I have a stock 05 (well i removed the muffler) see my sig) at about 2800 rpm wot i have a sudden power loss for a split second then it comes back to life it only happens in third and fourth and only occasionally i have not yet had a chance to stop by my local diesel shop but a friend of my said it might be a overboost sensor shutting it down but i throw no codes and never heard of this so tonight i'm gonna see if i can test my waste gate acuator so any help would be much appreciated