2014 F-150 SCREW, Ecoboost - 65K miles - towing boat.(tow/haul ON) on a mild incline

Accelerating onto highway (in normal drive mode), reached about 55, stuck behind a slow poke. Changed lanes and goosed it to get up to normal highway speed - 65mph. RPMs shot up to 5,000+ with no additional power. Had to back off accelerator and then try again, which then accelerated to 65 without problem. I am going to have dealer look at it, but any clues you can suggest before I go so I know what to expect. I don't recall having this problem prior to this. Thanks in advance.

 

Transmission slip?

 

You can pull codes to see if any exist.

It's possible the incident was entirely normal. If you goosed it a lot, it would have shifted down as far as possible. If you let off the gas unknowingly during the shift, it could have then not had enough power to actually accelerate. Truck will often leave the transmission in gear for a few seconds anticipating more throttle, which is often perceived as a failure to shift, or being 'stuck'.

 

I was thinking that as a possibility.