Disconnect the plug on top of the power antenna and check your amp draws again. I have seen that be an issue on several cars before. You can also pull out each fuse to isolate the culprit while you have your amp tester hooked to the battery. When the amp guage goes to zero you have found the draw. Although, if your car has a clock on the instrument cluster it is not unusual for it to draw low amps in order to keep the time while the car is not running. Hope this helps.