Hard starting 1999 Cadillac Deville


I have a 1999 Cadillac Deville with approximately 240k miles. The car runs great when it is running. The car is hard to start all the time and sometimes after I have driven the car for more than an hour and shut it off it will not start again. I basically have to leave it for sometimes an hour and then it will start but only after several attempts. What is causing this to happen? I have replaced the fuel pump and the fuel filter within the past 6 to 8 months. Could it be the EGR Valve? A friend said it may be the Crank Sensor? I am getting spark from the plugs. I have become so leary of the vehicles ability to start that if I am going somewhere I know I will have to shut the car off I will drive my 1966 Ford F-100 instead. Can you guys help?