If its expired its expired GM will not honor, it. Been there done that, And had to salvage parts and rebuild the engine from scratch. If any engine was built during the Covid lock down I would immediately send it back to wherever you bought it from.
It sounds like a grounding out issue. I had the same problem. I had to replace my fuel injector connectors they had become old and brittle and where arching under load. And the rule of thumb if you replace parts please use ACDelco I found off brands cause problems. More pricey but worth it. Hope...