I have an 03 with a 2.5 engine and 188000 miles. Overall the car runs great but occasionally it is hard to start. It bucks and sometimes backfires and even totally refuses to start. The last time this happened I had to spray in starting fluid and it eventually started. Once it starts it runs great. I have replaced the plugs and boots as well as the fuel pump. There are no check engine lights on or codes. Has anyone had a similar problem? Any suggestions?