I've been watching the third part of Return to the Pigsty recently. Did Erkang come back to life after his death?

Not dead. But thanks to the princess, in order to save him, the princess gave him life-sustaining drugs. This is also an expedient measure. Every time Erkang was dying, his soul would return to Wei Zi. At this point, his body is about to die. Every time, the princess saw Erkang dying. He will be poisoned. Therefore, Erkang didn't die every time. Until later, the doctors there cured Erkang's injury. After Erkang was resurrected, Wei Zi, Xiaoyan and others went to save Erkang.