Car won't shift into final drive gear on freeway. RPM high only going 80 mph max

You probably need trans rebuild , i would get a free check art aamco Or your trans shop .

Typically the transmission controller will sense the issue and put the transmission into a limp mode and turn on a warning light either the CEL or transmission light. How many miles on the car/trans. To diagnose this issue you need to connect to the transmission controller and read the faults, then pull the transmission pan and inspect the fluid and for excessive debris. Let us know if we can help you out.