[Zero10]

I'm not condemning the DME, let me make that clear first. That's a very expensive little box to change unnecessarily. I'm pointing my finger at the Fuel Pressure Regulator. First, check the vacuum lines to it. If they are disconnected, it will cause high fuel pressure (although it shouldn't be that high). If they are disconnected, try hooking them back up. You need a fuel pressure gauge to accurately diagnose this problem. If you can't find one that will fit the end of the fuel rail, you will need to drill a spare end cap to accept a normal fuel pressure gauge.

I don't believe all 4 are fired each time. I think they are fired in pairs. I believe the injectors are wired in pairs, in paralell. That's why disconnecting one works, if they were in series, the pair wouldn't fire, and it wouldn't help anything. If all 4 were to be fired at the same time, they would all be wired in paralell, from the same place.