I've recently had a small issue with my truck missing under hard load. If you're going around 40 MPH and push it down like merging it will kick back and forth and sputter and then start hitting fine again after a few seconds and move on. Possibly bad sparkplugs and/or wires? Thanks.
X2 If you haven't tuned it you must. Also look to fuel filter and cleaning your MAF. Check for clean tight connections in the air induction system. If you have a good code reader graph your pids and document your freeze frames.