The reason that you are having issues is that the 84 Cabriolet was a "tween" year auto.
Mid 84 was a mid year design change the major difference is that the Fuel tank went from 10 gallons no internal in-tank pump, to a 13 gallon tank with a in-tank pump. The way to tell is the Full Sized Spare tire, or the Space Saver Donut spare tire.
The 85 in-tank pump is what you want, as a matter of fact the Cabriolets use the same in-tank pump from 1984.5 to 1993.
This is also why you have to use both the 85 and 84 wiring schematic
All your cabby version questions can be answered at:
How to change the in-tank pump?