Man, there is a lot of bashing of the OP going on in this thread. I'm struggling to see how just dismissing what she is saying and repeating to go back to all stock is helpful.
First of all, she can't go back to the factory hardline, she has an edelbrock carburetor which has a different inlet that is located in a different spot. Telling her to buy a $400 carburetor to replace one that is working perfectly fine is ridiculous.
Secondly, I have had a very hard time finding an OEM mechanical pump with the correct fuel pressure lately. I bought a quality AC Delco replacement pump when I rebuilt my fuel system on my 80' K20 and was having a lot of problems. Fuel senders replaced, both tanks cleaned, new hose, new fuel pump, new fuel filter, and rebuilt the original Quadrajet. I could not for the life of me get the idle mixture leaned out and it ran pig rich all the time. I finally checked the fuel pressure and it was running 8psi at the low end and spiking up off the gauge that stopped reading at 12psi. The quadrajets really prefer to be down near 5 psi and certainly can't hold the seat closed at 8psi let alone 12 or more. This was all quality factory replacement parts.
Rather than spend time and money replacing pumps until I find one that puts out the exact amount of pressure I want. I put a filter, check valve, and adjustable regulator in line between the pump and carburetor and low and behold I was able to dial the fuel pressure down to about 5.5 psi and dial in the carburetor perfectly. My gas mileage went up about 3 mpg, it starts right up every time cold or hot, and drives much better than it ever did before.
