1995 Corvette starting problems

Here we go, my vette starts when cold, but dosnt when warm. I replaced fuel pump, plugs and wires, opti unit and cap an rotor about 1000 mi. ago. Now I am having starting problems. In the morning I will go out to the car and it will start fine. I will let it run for about 10 min. and turn the car off and will not start back up, it will just turn over. At this time I checked for spark at coil and no spark is present. I now have a new coil and ignition module, but same problem appears. I dont want to replace the opti unit again. ANY ADVICE...