2000 Kia Sephia - engine miss cyl 1

I have read through evey post here that I think relates to my problem, but none cover it exactly.

Here is the problem: My wife was driving the car, when the engine light came on. I had the OBII code checked and it was a missfire in cyl 1. I did have problems with both the spark plug and the wire. I changed out the spark plugs and replaced the spark wire. My wife then continued driving the car. The engine light would still come on, while at slow speeds (and flat road), and flash when driving (at speed, or anthing kind of incline at all). She thought I just didn't have the light turned off (even though the car was still running rough). She took the car by some friend of hers, and he suggested running a can of injector cleaner though, and dumped in a can of STP in an almost empty gas tank. She continued driving it for another week, and it got progressivly worse. Finially, she called me to have her towed home when she could not get it started one night after work.

I have checked the plugs and they seem oil fouled. I can get the car started sometimes, but it will only idle at 1000 rpm or less (mostly 750 rpm or less), and die out as soon as I touch the gas.

Any ideas on how to trouble shoot and fix this? I have seen may problems with missfires, and that was just a wire / ign coil / spark plug replacement. But I think due to the extended driving, I may have more damage now to deal with.

I'm still tring to find an answer to this -any ideas? Please?