N14 Stalling Issue Accelerator Problem

(Customer ran truck with bad alternator for a few days and apparently it ruined the ECM and wouldn't start until the customer replaced it. Now the truck comes into the shop with around 10 engine codes and stalling issues.)
The truck will not start without the accelerator depressed. Once it is running, it may run 10 seconds to two minutes and randomly shut off. The code 132 (DERATE POWER AND SPEED) accel. position sensor signal voltage low seems to be related to this issue as it is the only one active. It will put the truck in limp mode. I have gone through all the tests with the sensor, the wiring, and the ECM. Everything has tested good. But I cannot get the code to dissapear and exit limp mode. I have tried all the troubleshooting on Mitchell and Insight. So my question is, could the problem lie somehwhere else? The truck ran 100% fine before customer ran it with bad alternator and replaced ECM. I tried reprogramming the accelerator again (fully depressed slowly 3 times) but this has not helped. Anyone else had troubles with this? Customer also just changed shutoff solenoid with ECM. Thanks.