I have a 91 integra b18a1 with 138k on it. I recently did a head gasket, got the head surfaced, and timed. I have replaced the o2 sensor, distributor, cap, spark plug wires, spark plugs, ect sensor, fuel filter, radiator. I have a check engine light that comes on after start up and stays on. the code reads 43, Fuel supply system. My first step was the fuel filter, and that was not the problem. The car currently idles a little rough, goes from 500 to 750 rpms. Everything ran smooth before the blown head gasket. I am not sure what to replace next. I was told to replace the fuel pressure regulator, but not sure if that will do it. any suggestions?