I have a 97 Grand Am 4-cylinder. Sometimes when I start it up the engine stays on until I put it in gear and then it dies. Other times when I put it in gear it hesitates really bad and then if i press the gas pedal real hard it stops. This doesnt happen all the time but usually seems like it happens when it is really hot outside. When I am going speeds from 50 to 60 mph it hesitates a little bit as its accelerating. Its does this always. Any help would be much appreciated.