This is going to sound strange but you need to have the TPS checked with a scan tool or lab scope.
It has been shown that noise in the TPS of 0.02v or more may cause injector fault codes. If there is a speed control switch input to the Powertrain Control Module (PCM) that is shorted to voltage, it may cause the same problem. There have have been cases of a shorted clockspring causing this.
The TPS is the most common culprit for multiple fuel injector circuit codes on that model
Best of Luck
