Lexus Troubleshooting Questions? Ask a Lexus Expert
Has the check engine light been on recently? Or is it on now?
Do you have a code reader to see if there any codes set in the pending portion of the computer that would not cause light to come on yet may create some issues? In most states except California Virginia they do free malfunction code reads at most part stores or I can recommend a good generic code reader for less than $60 that you could buy and have. I recommend everyone have a code reader in the glovebox it will save you hundreds of dollars in diagnostic fees down the road.
Why you're getting the higher RPM is because you're not in overdrive at that point. It just won't help your gas mileage and you may have to dial your speed back a little bit if you don't want to hear the engine wind out at that RPM but it is not going to hurt the engine. Let me know if there any codes set in the computer in pending or in history.