Rough-idling 360, can't figure it out!
Fuel filters are supposed to be on the pressure side after going through the fuel pump.
So stock mopar Carter fuel pumps put out 6 psi. Your used fuel pump diaphragm could be stiff and stretched out, not giving you full pressure of 6 psi. May be time for a new Carter fuel pump.
Here is the one you need 23.00 plus ship. Do not need a fuel pressure regulator with these.
Summit Racing has the Carters and Jegs too.