2002 Toyota Echo • 191 miles

My name is moiz and I currently own a 2002 Toyota echo 1.5 liter engine. So the other day the car starting jerking and I realized it was time to change the sparks. When I took the old ones, they were completely out. I replaced it with some iridium NGKs. Later that day I was driving to school and it started to jerk again. So I took it to the mechanic and he diagnosed the check engine light. The error code came out to be P0305 cye #3 misfire detected. I want to replace the ignition coils myself so how do I know which coil exactly it is. And does the #3 indicate that #3 ignition coil went out? Thanks for your time and patience. Hope to hear from you soon.
March 8, 2013.

The fact that you have a misfire in the number 3 cylinder doesn't mean the coil is bad. Switch the coil with another coil from a different cylinder. See if the miss changes locations. Also, make sure the #3 spark plug is properly gapped. If everything checks out good, then you should check the cylinder for compression.