battery drain

I am now on my 3rd battery. 1993 Camry se v6 usa model.manual 5 speed.
Symtoms. Cars runs ok for 2 months. When starting after parked over night, the click click sound of a dead battery. Get a boost and runs ok for a couple of weeks and dead again after overnight parking.Avr test shows all ok. no drains. Replaced battery as a precaution. 2 months later same problem. We have power to the ignition but noticed poor starting due to the clutch safety switch not always allowing car to start. Could this switch allow the battery to drain overnight causing all my no start problems as it is integrated with the starter motor? Any help would be appreciated.