McALESTER, Okla. — Oklahoma administered the death penalty Thursday on a man who convulsed and vomited as he was executed for the 1998 slaying of a prison cafeteria worker, ending a six-year execution moratorium brought on by concerns over its execution methods, John Marion Grant, 60, who was strapped to a gurney inside the execution chamber, began convulsing and vomiting after the first drug, the sedative midazolam, was administered. Several minutes later, two members of the execution team wiped the vomit from his face and neck. Before the curtain was raised to allow witnesses to see into the execution chamber, Grant could be heard yelling, “Let’s go! Let’s go! Let’s go!” He delivered a stream of profanities before the lethal injection started. He was declared unconscious about 15 minutes after the first of three drugs was administered and declared dead about six minutes after that, at 4:21 p.m. Someone vomiting while being executed is rare, according to observers. “I’ve never heard o