I just got an 88 firebird the other day as a project. the car runs fine until it gets warmed up.. about 220 degrees. then it will act as if its out of gas, lurching and stalling when i give it gas. if i turn it off and right back on it'll run fine for a few more minutes then do the same thing. only seen the SES light come on once, checked it and its throwing codes 43 and 54. 43 is low voltage at electronic spark timing circuit. 54 is low voltage at fuel pump or fuel pump relay. the car seems to have low voltage all around though, usually around 13 volts. if i even turn the wheel to far without giving it gas it will stall. any ideas would be much appreciated. kind of a newbie here.
Car is an 88 firebird with 305 throttle body injection. auto trans