Rather an old thread but ref your water problem - I had identical problem with my 200SX when I got water over top of engine and had misfire. Water got down one of the spark plug tunnels and just sits in there under the rubber grommet, instead of boiling off. Took a long time before I found it. Regarding your overfuelling check your Lambda sensors, thats what caused mine. You wouldn't know except on full throttle when it went ballistic. hope that helps.