For the second time in four years, the M23 bus has earned the dubious distinction as the city's slowest.The crosstown Manhattan ride crept along 23rd St. at such a glacial pace Tuesday that a Daily News reporter on foot kept up with the vehicle for most of its Hudson River to East River run."I ran for this bus like a lunatic," gasped Lorri Greif, a fund-raising consultant as she climbed aboard. "If I'd missed it, I would do better walking across town."Moving at an average speed of 4 mph in noontime traffic, the M23 won this year's "Pokey" Award, a creation of the Straphangers Campaign and Transportation Alternatives.The snail-paced bus, which runs through one of the city's busier commercial strips, first won the award in 2003.The M34 bus, which navigates through traffic-chocked Herald Square, earned the award in 2004 and 2005. This year, the M34 came in second, with a whopping average speed of 4.3 mph.Besides the Pokeys, the advocacy groups issued a new award this year, the "Schleppie." It is given to the bus most prone to being late.The inaugural Schleppie went to the M1, which runs between Harlem and the East Village. M1 buses ran behind schedule 33% of the time, according to the groups."One thing that infuriates New York bus riders is waiting 20 minutes and then seeing three buses come in a herd," said Gene Russianoff of the Straphangers Campaign.Transit officials said Tuesday they were working to speed up buses and make schedules more dependable for its 2.5 million daily bus customers - including dedicating more bus lanes and installing new traffic signal technology.The News sent two reporters out to put this year's Pokey winner to the test. One climbed aboard an M23 at its first stop outside Chelsea Piers. A second walked east from the stop to the stop at the FDR Drive.Until Sixth Ave., the walker kept pace with the bus, often walking ahead as the blue-and-white behemoth stopped to pick up passengers."Sometimes it's just a mess," said bus driver Paul Calderon, 39, who has operated an M23 for seven years. While elderly passengers and construction crews can slow him down, "delivery trucks are the worst," Calderon said.At Sixth Ave., the bus pulled ahead. But at Lexington Ave., the walking reporter caught up to it.By Second Ave., emptier residential streets gave the gas-powered bus the advantage: It finished the 2.2 miles in 31 minutes, three minutes ahead of the reporter.