1990 gmc 1500 sierra 5.7 engine Seems its getting too much fuel and every time I press on the gas it wants to stall out.

I think you might not have enough fuel supply to the motor.replace the fuel filter if it hasn`t been changed for a while.then check the fuel pressure and volume with a gage and a container.if this is throttle body injection it should have about 13lbs pressure and the volume should be about 500ml in 15 seconds of running.if it was too much fuel you would be having black smoke out the tailpipe and wet plugs.

Have you changed the TPS sensor