I am hoping someone can help this newbie out. I purchased a 97 S500 two days ago and I figured I would give her a tune up and fluid change. After changing the oil, filter, and spark plugs and cleaned the engine bay with water, being careful to cover the MAS intake. I took her for a drive and after 35 miles the "Check Engine" light came on and she started to miss and sputter. It won't go above 4300 RPM's. I took it to the autostore and they retrieved the following codes P0300, P0304 and P1519
I then came home and change plug number 4 - No luck, still runs the same. Could it be the MAS?

Thanks
Kevin