Power Stroke Help

I have a 2003 F-350 with the 6.0 power stroke and only 143,000 miles. Recently I have been having an issue on and off again. No check engine lights or anything. I'm by no means a true mechanic but sounds like a waste gate coughing. Usually when I'm gradually accelerating it happens, but again, not every time. If I stomp on it picks up and goes. I've already had my ICP replaced along with an injector. I'm at a loss as to what to do but like all of us don't want to brake down. Any ideas would be greatly appreciated.