To all. It took a long time and going to a couple of shops, but, the code problem was finally solved. It turned out the MAF intake "batwing" was not communicating with the ecm correctly and the system had to be recalibrated to clear the codes. I took the car to Power Star Automotive in Greenville, SC. The owner is a former MB master tech and has the factory Star diagnostic system. It took them several tries to get the car to function properly. Thanks to all for the constructive suggestions and input.