I keep having a rough idling issue on my Silverado (5.3 liter v8 flex fuel) after high RPM for a short time. Happened 5 times within the last 30 days, 2 of which where while I was towing the boat the the others were when I was running late and flooring it. Sometimes the engine miss fire warning light came on, other times I could feel it. It corrected itself if I restarted the engine. Before this I had the downstream O2 sensor code come up, but this was due to "crap" build up on the airflow sensors and/or throttle. Any ideas on what this could be?