I had seven of my ignition coils go bad. Each time I got a check engine light with a P030x code. The x represents the number cylinder that a missfire is taking place at. In order to verify that the coil was bad you can switch the coil to another cylinder and see if the code follows and/or use a multimeter to test the continuity running through the coil. I forget the specs to look for but you can compare 2 or 3 good coil readings to the coil you think is bad. There is a thread on here somewhere that has more info. with the continuity specs. I hope that helps.
I had a 00 tundra w/ 130k miles. 1 coil went out. no big deal. 100 bux from the stealership's parts counter, and I was good. few months later, it happened again. Dammit. bought another coil and did the simple math. I could be in another 600 bux. no thanks.
sold it and bought used 06 DC for super good deal, cause no one wanted trucks cause gas was $4.50/gal here in so cal back in 08.
Moral of the story: just be ready, its a common problem for the earlier Tundras.