is it normal to run and hold 3000rpm at 65 to 70mph

You should be able to feel it shift through four gears which includes overdrive. If you can't feel it you should be able to see it on your tac as the rpm drops back with each shift. Another way is to manually shift it back down one gear at a time from overdrive. Do it slowly and carefully though. Let the car decelerate before dropping down into the lower gears and don't do this if you're in a bunch of traffic. If you don't have 3 gears plus overdrive, your next stop should be the transmission shop.