Gotta get this sorted out!

The volume test will only confirm flow at no back pressure so it may or may not tell you anything. If it is really low flow, then it is there. Which Edelbrock fuel pump do you have?

Sure sounds like a fuel problem... do you see the AFR's suddenly lean out when this happens? (Assuming you have an AFR meter...)

BTW, I read an earlier post about the exhaust note changing when the engine is hot. This can happen with a weak lifter check valve in a hydraulic lifter; the oil gets hot and thinner, and the lifter leaks down some, and the valve opening gets weak/lazy on that cylinder. We have had that exact thing happen....