Also check your fuel filter it might have some kind of gooey substance inside.
I had bought a old 48 Willys Jeep and it would run fine up to about 45 mph, then die.
If I backed off the throttle it would start running again.
It turns out instead of using a gasket to seal the Fuel Tank Sending Unit.
They used a silicone sealant.
The gas dissolved the silicone and it ended up in the filter.
It was acting like a governor, restricting fuel flow to the Carburetor.
What happens if you back off the throttle, does power come back?
Do you have the "can't see through" type of fuel filter?
That is the type that I had.
I had to cut into it to see the goo.
