In 1999 I had my bought-new-in-1985 Fiero GT rebuilt after being in
driveway storage, out in the open, for 6 years.

It was found that the gas tank liner was in barely acceptable shape but
within a year the tank needed to be replaced along with the fuel pump.
So you may want to do these things sooner rather than later.

I retired my GT initially after it developed a condition where it would
not run when warm, but that appears to have been leaking forward exhaust
manifold.

On my GT through its 21 or so years its main "problem" has been exhaust
manifold leaks and cracks, which tend to affect driveability when the
car is heated up. In each of three episodes where the car wouldn't run
well or at all when at operating temperature, a forward exhaust manifold
problem was in evidence.

During rebuild several areas proved needing attention:

1. Forward exhaust manifold;
2. Fuel tank and fuel pump;
3. Hangers and fasteners for underside cooling pipes, brake lines,
transmission oil cooler lines;
4. Alternator;
5. Brakes.

The brakes on my GT don't lend themselves to simple brake pad changes.
Typically reconditioned calipers have almost always been needed. Rotors
here in Canada are very cheap so one can also put new ones on for low
cost, although mine needed only turning at the last brake repair two
years ago.

Note that Fieros were recalled (automatics only however) for a problem
with the parking brake/piston actuator assembly on the rear brakes
causing the rear break self-adjustment to fail. All Fieros had the
problem but GM ducked the recall to manual transmission cars by casting
the brake issue as a "parking" problem. Automatics have transmission
locking pins, and the reasoning was they therefore did not need the fix.

As an owner, one has to allow for this issue on one's own.

I was advised many years ago by Transport Canada (I filed the only
complaint on the matter in Canada), that rear brake adjustment,
especially the proper adjustment of the parking brake cable, are very
important with these cars. The rear calipers do not adjust for wear on
these cars except when parking brake is applied. It was also my
impression that the parking brake design tended to seize up the
calipers, interfering with the rear brake adjustment in that way to.

Incidentally, there is a way to check if the parking brake is applying:
With a reliable engine running, park on a hill nose down. While holding
the brakes on, apply the parking brake. Then shift into neutral and
slowly release the brake pedal. If the car starts to move a problem
exists. Be careful, allow LOTS of space ahead and no cars or people in
the way.

This test does not verify whether the adjustment on the brakes is
necessarily working when the parking brake is applied, it seems to me.
My impression was that the adjustment may not happen possibly because it
is corrosion that can set in within the caliper mechanism.