93 gmc sierra 1500 5.7, sat for a while but was running great. the next time trying to start it starts up but dies just as fast. i have to pump the pedal to get it to start and keep pumping in order to keep running but still wants to die. it will not idle past 1500-1800 rpms. i replaced fuel filter, added new gas and added a fuel additive. also fuel gauge inop and oil pressure gauge jumps around when turning the ign. switch.

gunk in the system probably, try running it longer to get it hot. possibly the pump?

Thanks for the advice. After more trouble shooting I got a code 54. I have low voltage at or to the fuel pump.? Could the fuel pump relay be bad? or just the pump going bad.

it more than likely is the pump, it may start working properly again if the tarnish cleans out of it from sitting. try to run as much as you can thru it.
but it doesnt really sound major at least.