[mysocal911]

Originally Posted by wazzz

There are no grounds as such for the injectors, since the injectors get their "ground" as the signal that is pulsed from the ECU. The other terminal of each injector gets a permanent +12V power whenever ignition is on.

Since one bank looks much leaner than the other one, it may be worth checking the signal line that carries this pulsed "ground" between the ECU and the connector pin for this bank. Do the same for the other bank as a comparison. You need to do ohm tests while the ignition is switched off. Even a small stray resistance is significant, as these lines carry high currents.

Easier way to do these checks would be to disconnect the big connector at the ECU under driver seat and ohm between pin 14 and pin 5 on the injector loom connector. Do the same between pin 15 (ECU harness connector) and pin 6 (injector loom connector).
Injector loom connector is on the cross member near the left shock tower. It is a six-pin connector, but only four of them are used. Two for power, two for pulsed ground signals.

As a side note, both signal lines are tied together inside the ECU, so the six injectors are actually driven in parallel. In your case, it appears that one signal line is weaker than the other one.

Or there's an intake air leak on that bank.