By Thomas Tracy From New York Daily News NEW YORK—An irate McDonald’s customer stabbed another customer in Midtown Manhattan following a dispute over the amount of sweetener in his morning coffee, police said Wednesday. The 57-year-old victim was eating inside the McDonald’s on Eighth Avenue near W. 35th Street about 8:20 a.m. Tuesday when the suspect complained his coffee was too sweet, authorities said. An argument erupted between the two customers and spilled outside the fast-food joint, where the suspect pulled a blade and stabbed the victim in the chest, officials said. EMS took the victim to an area hospital where he was treated for a minor injury. It was not immediately clear why the victim was targeted by the accused stabber. Police were uncertain if the victim gave the suspect his coffee, or if the victim tried to intervene after the suspect began complaining. The suspected stabber, described as …