92 runing rich

i have a 92 s10 blazer 4wd with a 4.3 cpi....when it gets to opreating temp it starts to run rich and boil out black smoke...driving down the road it surges eg. not enough fuel?...i replaced the egr,plugs & wires,rotor,cap,and o2 sensor....i placed it on a computer it showed a code 45....acording to the dignostic comp ..everythimg else was within specs..anyone have any ideals??? thanks

the fuel pressure regulator was bad....showed 92 psi