1998 Eclipse Not Starting

1998 Mitsubishi Eclipse GS, 5spd Manual, 85,753 miles. I need some help. The starter and alternator have been replaced within the last 2-3 months to fix an apparent problem with the car not starting. Well, the car won't start again, both the alternator and starter were checked and are fine. Also, the battery is not keeping a charge, strange because it is an Optima Yellow Top. I have made no aftermarket modifications to the car that would change the complexion of the engine, transmission, etc. When I try to jump start the car, it turns over but doesn't want to start. It sounds as if the engine is not getting enough fuel through the injectors and into the combustion chamber. I don't know if this is an electrical problem or something to due with the fuel injectors, fuel rail or fuel filter. Can you PLEASE help me figure out what needs to be done in order to start driving my car again. Thanks.