msisk14

I have a 91 LX 5.0 andI am not getting any injector pulse. I have checked all the relays, changed my fuel pump, changed the fuel filter, checked for spark, checked fuel pressure, even checked all my fuses and connections. If the car sits over night the next morning the car will start. As soon as I turn off the car the car wont start again. I have been told it could be the computer but why would it start sometimes? Any suggestions?