I have a 1982 Camaro, Z-28, Pace Car with cross fire injection. This car started idling rough. I did the diagnostics on this car and it showed a code 42. This indicates a ignition module problem or a problem with the ECM. I have changed both and the results are the same. I have checked the fuel pressure and it reads approximately 4 PSI for 2 seconds. When the motor is turning over, the pressure guage reads 0. What other options do I need to look at. Thanks