Engine missing 0300 code

[Eaustin494]

I am about ready to sell my truck. I get the dreaded 0300 random Cly . Misfire code. I have replaced the plugs, cap, rotor, distributor, ignition control module, coil, cam shaft position sensor (keep getting this code too), crankshaft position sensor, and yesterday converted it to MFI with a new spyder that came with a new fuel pressure regulator. Today I get the 0300 code again and when I drive above 40 is randomly misses. Does anyone have any guess what might be wrong before I light it on fire in the driveway?
Thanks Eric