adkaven

I have a 1993 si and for the last couple of weeks my engine has been acting up. I checked the code and it was a 43 for fuel supply system. The idle is rough sometimes it sounds better sometimes worse. Most of the time the check engine light comes on after about 5 mins of driving over 50 mph. After the check engine light comes on it seems to run worse. Also when it is about 80 degrees in temperature outside the engine likes to die whenever i stop. I never have problems with it starting though. Also whenever i let go of the gas it jerks a little. I did change the fuel filter and I did put some seafoam in it and my dad said the injectors are fine. And the first thing i did before i checked the code was change the spark plugs. I seriously don't know what it could be any help would be appreciated.