Loss of power Options

[BfloRandy]

Hey gang, just wanted to beg for your thoughts on my latest issue!
'75 2.0 dual Weber 40's.
Was on the highway the other day and the engine suddenly got much louder and I began losing power. (I was doing about 65 - 3k rpms 5th gear) I dropped down to 4th, and the issue persisted. Got off the highway and pulled into a parking lot, fiddled with the carbs a bit, and got it running what I thought was normally again. Within a couple minutes of returning to the highway, the problem returned. Same thing, got off, tweaked the carbs again, and this time I was good until I got where I was going. On the way home, I avoided highway speeds, and all seemed ok to get her home. Took her out a couple days later on city streets and had the problem the whole time. The loud engine noise is no longer present, btw. Idle would drop to almost nothing, in fact at lights, I had to keep pumping the gas pedal to keep from stalling. She's been parked now for over a week, and when I have to switch sides of the street for parking, sometimes she behaves and starts up normally, other times it's a battle, and I have to keep pumping the gas to keep her alive until she "catches" and idles normally so I can move her. I don't know where to start looking for the problem. I'm thinking carbs are way out of whack, could also be a fuel supply issue, sticky valve, or maybe an electrical short? The thing that gets me is that it seems to be an intermittent issue. Intermittency seems to me to rule out the carbs unless it's a float sticking. Having to pump the gas tells me that it isn't likely electrical. If there's a fuel line pinched, it'd stay pinched. Scratching head...