Why do my RPMs randomly jump up about 500 momentarily while cruising on interstate?
The RPM jump up for a short distance and then drop back down. The car
doesn't downshift from over-drive.
That sounds like the lockup for the torque converter is cycling, hard to say what it might actually be, you will need to have the transmission control systems checked, a good transmission shop can do this, they can plug in and run the tests independent of the vehicles control and that will help determine if it is an internal transmission control solenoid, the TCM unit, or wiring. HTH
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