There is conflicting information about throttle bodies for the 2.5L Fiero. Some sources say that all GM 2.5L engines from '84-86 used the same throttle body. If you have a convenient salvage yard it is worth checking. We have not confirmed this and offer the information below from the "Hollander" manual:
'84 2.5L According to the Hollander manual, the throttle body in the '84 Fiero is unique - no equivalents. However Frank Catalano advised that the '82-84 Corvette, Camaro and Firebird equipped with the Crossfire injection system used the same TBI unit as the '84 Fiero. What's more, these throttle bodies can be bored and modified for increased horsepower. Boring service is available at crossfireinjection.net as of April 2010.
Throttle body assemblies from '85-88 Fieros will not fit the '84.
'85 2.5L Throttle bodies from the following will fit:
Chevy Blazer S10/GM Jimmy S15 '85 2.5L S10/S15/GM Sonoma '85 2.5L
'86 2.5L This throttle body is unique to the Fiero. No equivalents. Throttle body assemblies from '84-85 or '87-88 Fieros will not fit the '86.
'87-88 2.5L Throttle bodies from the following will fit:
Buick Skylark '87 2.5L Buick Somerset '87 2.5L Olds Calais '87 2.5L Pontiac Grand Am '87 2.5L
'85-88: This throttle body assembly, made for GM by Holley, is unique to the Fiero. No equivalents. If the throttle body needs to be replaced, use one from a donor Fiero.