Jeep Strokers

On my Idaho trip (pulling a 3500# travel trailer), I noticed that if RPMs were 2250+ and I mashed the pedal down near WOT (but not to kickdown) it felt like a kick in the rear. Without the trailer it feels like afterburner. I was thinking fuel pressure regulator, but I would expect that to be more gradual. Now, I'm wondering if Renix has something to do with it. I once built a 351 Cleveland (carbureted) for a Ford camper van that had a similar phenomenon, but I attributed that to exhaust tuning. The Jeep has a Borla header and a straight-through (cherry bomb) muffler, so that is still a possibility, but I still wonder if the ECU has a special case for WOT?

Any ideas ?

Thanks...

Open loop at 70 to 80% throttle.

That could explain - I'll have to study it more (thanks for the link) before I can say I understand it. Thanks!