Failure to Start

What is your question?

I just bought a used 1995 Saturn sl2 and put a new starter, fuel regulator, and spark plug wires on car and cannot get it to start 99% of time; it starts after it has sat for a long while. Can anyone please tell me what the problem is and how to fix it? When I try to start it, all it does is crank over. Once in a blue moon it will start and run fine, but it dies again shortley after, then will not start, again, for a while. I am begging... PLEASE SOMEONE HELP ME!!!!!