Odd Stutter Today on 2019 - Help Diagnose Please

2019 OR DC 4v4 with AT.
I'm going about 70-80 in 4th gear in S mode.
I'm at about 4000 RPM giving it about 60% throttle
Flat highway, not high elevation.
It stutters as if for a second it wasn't getting air/gas and then it lurches with a loud thud and keeps on revving.

This wasn't the switch over for valves/Atkinsson etc, just seemed to "die" for a split second and then thud back into revving.

At those #s it wouldn't be going back to 3rd and it didn't shift, it was very odd.
Almost 700 miles on it.

Thanks in advance.

If you're wondering why I was driving like that, I believe in varying the RPMs and throttle during break-in, which is up to 1000 miles on the vehicle.

 

Never heard of breaking it in like that. I just let the variability between "city" driving and driving in the country take care of it. I would feel uncomfortable driving that kind of distance with the RPMs so high in a brand new rig.

 

Agree...

Breaking in your new Toyota
To extend the life of the vehicle, observing the following precautions is recommended:
●For the first 200 miles (300 km): Avoid sudden stops.
●For the first 500 miles (800 km): Do not tow a trailer.
●For the first 1000 miles (1600 km):
• Do not drive at extremely high speeds.
• Avoid sudden acceleration.
• Do not drive continuously in low gears.
• Do not drive at a constant speed for extended periods.

 

Trucks in the learning stage an was prolly shocked .

 

Appreciate the feedback. Let me say this - I have put in a ton of time over my adult life researching proper engine break-in. I've frankly kinda went OCD on it. There are two schools of thought:

a) Baby it
b) Drive it like you stole it

Going further, you have people with opinions on factory break in, break in oil, using mineral oil, using conventional oil, I mean if you wanted to research the schools of thought on break-in you could literally read for weeks. I was just reading an article today that had a case that it's bad to change oil early because the detergents don't activate until 1000 miles on it and, while I don't agree with it, it was well-written and Im sure there are folks that do subscribe to such.

From all of this, I have come to a break-in procedure that I am comfortable with.

However, almost every article/YouTube video agrees on the following:

Vary the RPMs and load, which I do
Wait for the engine to get to regular operating temperatures.

I also vary the accelerator input but I don't push it all the way down, I don't take off from a stop quickly and I don't redline the engine. I also realize that transmission/differentials have to be broken in as well, typically with heat cycles for the rear diff.

On a 6k redline engine, being at 3k in 3rd gear and giving it some gas and going to 5k I would not consider to be breaking what is in the Toyota manual.