I think that if that was the problem, you'd be getting lots of other problems too. It's a good idea to clean it anyway. I couldn't tell on my car, but if the cable connects to iron, definitely clean it anyway. If you have some, little dielectric grease might keep corrosion away longer, too.
In my second post I said that the computer grounds the injectors to make them fire. It's the other way around; the injectors are grounded and the ECU applies positive voltage to them. I guess that implies that the computer power leads need to be checked too.
If the problem isn't in any of the wiring or sensors, the only other thing that comes to mind is a failing injector driver in the ECU.