When the car starts to misfire, you will feel a loss in performance. What you can do, is start with the simple stuff. With the car running, take out each spark plug wire(they are called coils, you have three, one for two cylinders), the ones in the front are actual coils, the ones in the back are just plug wires that are fed off the three coils in the front. You can take one coil out at a time to figure out which one is bad. While taking one out with the car running, notice if once you remove a coil the car starts to run or sound funny, if that happens, then you know that coil is GOOD. Try it with another one, if the car runs funny when u take it out, that coil is GOOD. Try it with the third one, if you take it out and the car does not sound any different or runs the same with the coil out, then that coil or plug is bad.
If you located the bad coil, take it out. Inspect the rubber ends where they connect to the spark plug VERY carefully. There will be a small small pin size hole somewhere, that is where it is arching electricity and not going to the spark plug to fire the cylinder.
If your cheap or don't have money, because one coil and plug wire for two cylinders(because remember, one coil is for two cylinders, with the coil in the front and the plug on the other side) can be expensive. You can do a little red-neck repair to buy you some time. Take some electrical tape after you have located the small pin size hole and wrap it two or three times around the hole. Don't do it too much or the coil or plug wont fit back into the spark plug hole. It will buy you a lot of time until you can get it fixed.
If it's not a coil pack, then its probably the TDC sensor. But this is good information if you are ever driving somewhere and you have an electrical problem. I actually had to use this when I was driving to san diego, I had one coil go bad and figured out which one it was, wrapped it with electrical tape and I was good to go all the way there with no check engine light. GOOD LUCK!