Cold Start Headache's

Sup I have a 76 280z 2+2 stock I2.8 and every time the temp outside drops below 40deg. It wont start what it will do is crank and crank and crank then I'll here a click and then it will start but not everytime and only in cold weather I have tested my injectors my cold start valve Ecu Replaced my coil and my ignition control module. I'm really stuck on this if any body got an idea's I would be greatful