[old_master]

The fuel pressure regulator, (under the upper intake manifold) restricts the fuel flow which allows the fuel pump to build pressure. Regulators are factory set anywhere from 60 to 66 psi. When that pressure is achieved, it bleeds off the excess fuel & pressure back to the tank and maintains a constant pressure at the injectors. The injectors will not open below approximately 57psi, sometimes as low as 55psi. The fuel that you pour in is enough to get the engine started and run half way decent. If the fuel pump can not build at least 60psi, you'll have driveability issues. Your 58psi is below that threshold. Does the pressure hold after the pump shuts off?