I heard that there is a pre pump that helps the fuel pump out that may need checked on too. What would they be referencing? I've never heard of a pre pump to the fuel pump.

The gas tank is above the pump in the 4kq, and the tank feeds the pump from the bottom of the tank.

So no need for a pre pump..

(When the fuel outlet is from the top of the tank, (or the high pressure fuel pump is above the bottom of the tank) some setups have a low pressure pump to deliver fuel from the tank to the external high pressure pump.)