PHXGT,
So as not to steal your post, have you noticed the door ajar light coming on for a split second when you hit a bump? The light is hard to see in the daylight and also because it is hidden behind the steering wheel. Try driving over the same bump at night and have someone look at your warning lights to see if it blinks. My bet is the front lid is not locked down. I had this same problem the other day and it turned out to be the front hood/trunk was not latched all the way. So, every time I hit a bump in the road, the door ajar light would come on for a split second and the alarm would chirp.
As the car mechanic's adage says, always start with the simplist cause first before you start changing parts and overhauling the engine just because a spark plug wire was loose.