Overdrive doesn't work all the time

@johnjones44160 try to put this all in one question. Tell us a story. Start by telling us what year your RX is (and we assume it has a 3.0l engine. Now, what exactly is it doing? What does or does it not do? What have you checked and what have you tried? Just a handful of loosely associated words are not sufficient to give you a working answer. Help us to help you by telling us all about it :-)