My son's vehicle. The alternator failed. He tried to make it to the next exit but it died. He had it towed home and replaced the alternator. The new alternator installation went well, and after that, it ran normal and charged strong, but it wouldn't idle. It would stall if you let your foot off the throttle pedal. While we were diagnosing that symptom, it got worse, and now it will start, but immediately stalls after 1 to 2 seconds. It will keep restarting, but will not stay running. Even with throttle input, it revs, but then dies, each time like somebody hit a kill switch. It sets only one code P1155 which is for a limp home valve malfunction. We swapped the throttle body assembly (which includes the LHV) and no change. We checked the wiring continuity from the LHV to the ECU and that checks out good. The system will not allow my Actron scanner to clear the P1155 code. And interestingly, when we disconnect the battery to hard clear everything, the P1155 returns on the next key on, before even cranking. We are totally perplexed as to what could be going on here. Does anyone have any suggestions for what we could investigate next. Thanks in advance for any advice!