Hi,
I have an issue with my shifting, and want to confirm that it is the "Transmission mode switch", or if it is something else.

What I am experiencing seems to happen at around 26/27mph, almost always on level or near-level ground. I will be driving along, not accelerating too aggressively, and right around 26 mph, it seems like the transmission misses a shift to the next gear. I end up revving the engine in order to keep accelerating.

I then have to back off the gas so that the car drops back down in speed below 26 mph. Then, I can usually accelerate again past 26 and it will shift into the next gear that it missed the first time.

Is this the "Transmission mode switch", or something else?

Any suggestions are appreciated.

Thank you.