Mine (very early '04) will do this if you catch it just right. Pretty scary when you are towing the trailer, start to pull around someone, slam the gas and ... nothing ... for about three seconds.
I can make it happen fairly consistently under these conditions: rig rolling on flat ground in Manual Mode about 35-40 MPH and trans set to Gear 3. Ease up for a couple seconds ... then SLAM the gas to the floor.
Always seems to happen if I don't force a downshift beforehand (I always tow in Manual Mode).
It acts like a code interchange problem between the engine and transmission, and the vehicle is in a speed range where the trans doesn't have clear programming to downshift. If the transmission is already rolling in a lower gear, it's ready to take the engine speed and even step down another gear if necessary. But if it's not, everything hesitates until you get the downshift.
Already have tried new plugs, clean air filter and MAF sensor, new manifolds.
Will be interested to see how this turns out.
Only way I've ever been able to get around it is to not SLAM the gas to the floor, but to take it part-way down, then full down.