Brake booster diaphrams tend to go hard after a while. Could have a vacuum leak to the booster. Brake pistons could be gooped up in the bores.
My '88 Formula brakes never worked well when cold. Worked fine when warmed up.
Oh well...
Oh yeah, never was an SE in '88.
Lineup was--
Fiero -- notchback with 4 cyl,
Formula-- notchback with V6,
GT-- sloped nose, fastback with V6.