when driving my car the engine sounds like it is revving high to eliminate this i have to step on the accelerator for it to stop does anyone know what causes this

How many RPM's is the engine turning at 60 mph?

There is no RPM guage on a Prius, so no way to tell the RPM...

I have the same problem, and Toyota looks at me like I'm a crazy person, even AFTER they witnessed the problem. They can do NOTHING to fix it. They want me to replace batteries, replace throttle controls, O2 sensors, etc. etc. at a cost of several thousand, and they admit they have no idea if it will fix the "the problem".

While driving my 2015 Prius, there are randomly high RPMs. This happens on the highway and at slow speeds too. What could be causing this?

Did you get an answer Cindy I’m have the same issue. Mine is a 2015 too.

any updates on this please?

I had the same thing and they replaced the intake manifold and reflashed the ecm. It fixed it. Mine would rev to full rpm when I'd take my foot off the gas, then go back to normal when my foot was on the gas. It was sporadic, and they couldn't replicate it until the third time I took the car in.

Also, it was $811.23 for the fix.