My truck runs perfectly fine then out of the blue it gets really loud and goes through revs really rough. Still shifts fine and doesn't jerk. But it kind of feels like it loses power when this starts happening. Then it goes away runs fine again and returns randomly. I just had the tranny serviced and there was no shaving's and everything looked clean. Just last week changed the cap/rotor/wires/plugs to see it made any difference and still nothing. Any ideas to what's causing this? It's the 5.7 tbi engine.