I have a 96 Rav4. When I am driving on the freeway it will get stuck at 3000 RPMs for a good 20 miles. It doesn’t do it all the time, but it does it a lot. The car will only be going 50 mph, but its stuck at high RPMs. The mechanic has no idea what is going on.
Sounds like there could be something wrong with the lockup torque converter. It would probably be higher than that in 3rd at 50 mph
There is a button on the shifter, it turns the overdrive on and off and all Toyota’s have one. Perhaps you are hitting the button without knowing it? When overdrive is “off” there should be a little yellow “OD” light that lights up on the instrument cluster.
If you are familiar with this button and feature on your car - never mind. If this is new info to you find the button and experiment with it on and off and see what happens.
When you say stuck…you mean like “cruise control”?
Mine doesn;t have the OD button.
But I agree with everyone that it sounds like the car isn’t upshifting, and if the car has the OD button that should definitely be checked out. I’d also suggest that the OP check the tranny fluid for level and for color and smell.
I ahouls point out that my car at 75 mph with cruise control on just stays at 3000rpm. It has enough oomph not to have to downshift going up most inclines to maintain its speed, so it just sits there. Certainly I’m sure the injector pulsewidth elongates a bit to maintain speed, but not so as to require a downshift. Perhaps that’s what the OP is seeing?
Time for a new mechanic. Ur car is in 3rd gear, not 4th like it should be. Take it to a transmission shop. If the tech tool says trans is being told to shift to 4th and it will not. Than u have trans issues.