How's this for a quandary!

[GTVeloce]

So, a few days ago the car wouldn't start. Whilst trying to diagnose the problem, I had all four injector plugs off and was checking on voltage at the injector plug when it started and ran for about 5 secs. So, I reconnected two injector plugs and she ran, albeit rough. Plugged the last two in (whilst the engine was running) and it smoothed out and ran perfectly.

Since then I have had the car fail to start about 50% of the time and all I do is pull two injector plugs, start the car then reconnect the two plugs. Once the car is running she runs as well as ever.

Has anyone come across this or have any idea what could cause this?

[GTVeloce]

I should have mentioned the car is a 75 TS.

Still completely flummoxed why the car will sometimes only start effectively on 2 cylinders.

[MD]

Wild guess.
You have a poor electrical power supply to all injectors from the battery. There is just enough grunt to fire two. Once the motor is turning, it spins the alternator which adds sufficient power to overcome the shortfall and all the injectors become operational.

Be sure you circuit trace all grounds and B+ connections relating to injection.