2001 Ford Station Wagon

Transmission problem
2001 Ford Station Wagon Front Wheel Drive Automatic 83000 miles

Last November, my check engine light came on and I took it to my mechanic. It was running rough. They replaced the spark plugs, wires, #1 fuel injector and ignition coil and flushed the fuel system. Check engine light has come on again and car is running rough. I took it to autozone to read the code and it says the # 1cylinder is misfiring. I am taking it to the mechanic tommorrow. How could this happen again in less than a year? Could there be bigger issues with this car?
October 11, 2009.

Misfire at a specific cylinder check the sparkplug, compression and fuel injector for that cylinder

Oct 11, 2009.