My old 2001 V6 had this problem. I replaced plugs, wires, and fuel filter first and it still continued. Ended up being the coil pack. Went to autozone, spent like $50 or whatever it was back then and it cleared right up. My symptoms were misfire and slow reaction under medium/heavy load at low rpm.
I don't believe mine threw codes when this happened. It was almost like the ignition system was working, but didn't have enough spark to the plug to ignite the fuel at medium/high loads. I could accelerate slowly, cruise, and idle fine. I could even smash the peddle at high rpm and run fine. but low rpm with a lot of fuel going to the engine was the problem.
I would change the plugs and wires and filter especially if you're getting up there in miles. if that doesn't do the trick, go for the coil pack. This was probably 4-5 years ago, but if i remember correctly, the symptoms got worse over time as the coil pack starting failing more and more.