coil packs

have a 2000 sienna that has had coil packs replaced twice in less than a year. the first time about 2 months after we bought. bought it used with 69,000 miles. other than this very happy with the van. not really interested in having to deal with coil packs once a year. any advice?

What are symptoms of bad coil packs? I have a 98 sienna that has 155k on it and the engine idles like crap. Otherwise it has been very reliable.

depending on how many coils in the pack are bad, you can have anything from loss of engine power, to rough idling, to no start conditions