When you say "disconnected the E-DIFF", what did you disconnect exactly? To really eliminate the E-DIFF you have to disconnect both hoses from the quick couplings. A lot F430s start to suffer from internal differential leaks. If after disconnecting the E-DIFF hoses you still have the same pressure drops, then you know for sure that the problem is at the F1 side. Pump cycling every 120secs with engine off is not normal. With engine off, the pressure should hold a very long time, I mean hours.