Start simple 1 = fuses clean them all 2 = Earth points clean and grease , then refit the bolt.Look for vacuum leaks . Now get a fuel pressure check .Do you see any fuel leaking in the area of the fuel distributor ? . Come out at night in the dark and start the car up now look for sparks tracking on the ht leads .coil, and distributor top . Shorting can be coming from the plug and cylinder head if it has oil in the plug holes due to valve cover gasket leaking .