OK, lets start off the easy way. There are several TSBs (technical service bullitens) for your car that could be the cause. These are the best place to begin. Have you had any of these done?
Camshaft Position Sensor
Fuel Pump
2.5 Starter Replacement
Not saying any of that could be the cause, but it is possible. Read them and see if any of them fit your problem. Won't "warm start" or no start after "cold soak" etc... Maybe something will be able to help.