I had this intermittent starting issue. It will come up again and at the worst times, like a beautiful Saturday morning when you want to take a long drive. Go through whatever else you want to check but in the end it will be the relay control module. You may think that you've found another cause but it's unlikely. You can't really check the module because most of the time it's working and it won't show up on the error codes in the computer for the same reason. Please read all the posts on this issue and they will tell you everything you need to know about this issue. You can buy the part and do it yourself or just have the dealer do it. I think mine cost $350 installed. (I knew you had to have an '04 because that's the one that seems to have the problem; I just checked and sure enough you do have an '04.)