need help getting my KA24E running right

[Scudd]

I have a 1991 240sx and I dropped a KA24E in it. It only has about 50,000 miles on the motor, but it had been sitting in my friends garage for about two years. We set the motor down in there and ran it for a couple of days and found out the bearing inside the distributor was shot so we put a whole new distributor in it and it fired right up, ran perfect, then the distributor that was in it wasn't the right one. So we took it out and put another one in it, the right one, and it fired up and ran perfect, then the next morning I got up and went outside and tried to crank it and it will turn over but it wont fire up . It's not the distributor so what is it? The only way it will fire up is to push it off, it wont crank by the ignition. Once you push it off it will run fine but then it wont start back up the next day, unless you push it off. Any suggestions?? Please tell me!!