METS 5 GIANTS 2 Mike Pelfrey's stomach virus is history and maybe, too, thenausea he was giving his manager every fifth day. Yesterday the right-hander pitched a Cinco de Masterpiece. Thatmeant working into the eighth inning for the first time this year.It meant working with confidence and getting the Mets a victory to conclude athree-game series against the defending champions. "Nice and easy and almost effortless," Pelfrey said after the Mets beat the Giants 5-2 at CitiField. "When you have games like that, you come out and you're notreally sore - your body is not really sore."