I don't think the flaw was the trucks. Highly unlikely 3 different trucks would display the exact same "problem". As said before the only common denominator was the driver.

If the engine revved to 4,000 RPMs at startup with out any commands from the accelerator you would've gotten the powertrain malfunction indicator. The commanded throttle opening would've been vastly different the actual opening and the truck's computer would've recognized that as a fault and went to limp mode and set a fault code.

You said you don't drive with a lead foot but driving off the dealer lot you floored it, probably with a cold engine and transmission. Couldn't wait to "see what she can do".

 

You know it would be nice to post on this forum ONE time without someone saying I was not telling the truth. To make my original post shorter I did not mention that the Lariet loaner did the revving trick more than one time. Twice more in fact. Both times as I was accelerating normally, entering traffic. By the way, I got 20 mpg (half street/half highway )for the 3 weeks I had that loaner. It was a 4x4 with a max trailer package, so I drove it with a pretty light foot. But it really doesn't make any difference, it should not happen. And is in fact dangerous. And it is indeed a "problem". If I can drive with a light foot, a lead foot or anything in between and it stays at 4000 rpm when I remove my foot from the gas and the pickup slows down, it is a fault. I may have caused the problem, but I wasn't at fault.

All three times I was on a city street, no way I could "see what she can do".

 

If they were all brand new trucks, then there is no "learned data". The truck learns your driving style over time and mileage. The engines and transmissions were probably running at the default factory tune and had no data to work off of. This behavior will settle down after you put several hundred miles or so on the truck.

 

Audi had "unintended acceleration" issues in the late 80s. Turns out the placement of the brake and gas pedals made some drivers nick the gas pedal while applying the brakes. I suspect something similar. I had my foot on the gas pedal in my 2009 f150 one time while starting it. Rev'd right up to 4000rpm before I could react.

https://embeddedgurus.com/barr-code/...-acceleration/

 

You aren't alone.
I thought this very same thing happened twice about a month or so after I took delivery of this 2018.
Barely touched the throttle to start out on icy driveway engines revving way high yet no power to rear wheels.
This didn't happen right at start up either, truck had been warming up running 5 or ten mins already but happened on the first shift into gear from park.

 

I have a 2014 f_150 xlt 5.0. I was driving down the highway doing about 70mph and needed to pass someone fast so I punched it truck shifted down and reved up and didn't have take off lost all momentum until I let up on gas and truck returned to normal.. tried it again and same thing happened. Truck shifts fine and pulls it self fine only does this when you punch the gas really fast..