Thanks for the info. I have taken this car to a local general repair garage and I've spent $1200 trying to correct the problem. The last time, they told me I could fix it myself because they had already run my bill up to $540 replacing coil springs and strut mounts, to pass the Pa safety inspection. I have had a lot of older cars but never a computer problem like this. I'm going to take your advice and replace the coil pack - and I'm going to switch #1 and #4 injectors to see if I get a P0304 code instead of a P0301. If so, it would indicate a bad or plugged injector, right? Here's a question - how does the computer know which cylinder is misfiring? Is there a sensor on each cylinder? If the coil pack uses the "waste spark" system, and each of the 3 coils fires 2 cylinders on every revolution, why don't I have 2 misfiring cylinders?