The88 V6 or any Fiero V6 pump won't work in it, but unless the harnesses are different, they should work. Ashby replaced the one in my 88 coupe with a used one, but I don't know what year it came from.
According to The Fiero Store, the same pump fits all year 4-cylinders. Rock Auto agrees, listing the same numbers for both 84 and 88.