The loss of power every 10 seconds is likely due to the vacuum fuel pump drawing fuel. There should be a fitting on the intake manifold that has a much smaller hole that the tube size to minimize the loss of vacuum when the pump is drawing fuel. If that is not in place there will be a much larger loss of idle speed when pumping. The float on a 4 screw vacuum tank has a straight section on the float wire just below the upper bend. That gives a longer time between pumping cycles as the float can move further up and down before it activates the valves.
You need to adjust the carburetor idle mixture to the maximum idle speed without hesitation on acceleration. The wear on the throttle shaft and carburetor body usually results in fewer turns out on the adjustment screw. Many RAKX-0 carburetors have the screw bottomed out or nearly so to idle well. The RX-0 not so much.
| 
